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{{Short description|Order of insects}}
{{for-multi|the car|Volkswagen Beetle|other uses|Beetle (disambiguation)}}
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{{Redirect-distinguish|Coleoptera|Coeloptera|Cleopatra}}
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{{Use mdy dates|date=September 2012}}
{{Automatic taxobox
| fossil_range = {{Fossil range|299|0}}<small>Earliest [[Permian]]–[[Holocene|Present]]</small>
| image = Coleoptera collage.png
| image_caption = Clockwise from top left: female golden stag beetle (''[[Lamprima aurata]]''), [[rhinoceros beetle]] (''Megasoma'' sp.), long nose weevil (''[[Rhinotia hemistictus]]''), cowboy beetle (''[[Chondropyga dorsalis]]''), and a species of ''[[Amblytelus]]''
| taxon = Coleoptera
| authority = [[Linnaeus]], [[10th edition of Systema Naturae|1758]]
| subdivision_ranks = Suborders
| subdivision_ref = <ref name="Bouchard_et_al_2011">{{cite journal |last1=Bouchard |first1=P. |last2=Bousquet |first2=Y. |last3=Davies |first3=A. |last4=Alonso-Zarazaga |first4=M. |last5=Lawrence |first5=J. |last6=Lyal |first6=C. |last7=Newton |first7=A. |last8=Reid |first8=C. |last9=Schmitt |first9=M. |last10=Ślipiński |first10=A. |last11=Smith |first11=A. |title=Family-group names in Coleoptera (Insecta) |journal=ZooKeys |date=2011 |issue=88 |pages=1–972 |doi=10.3897/zookeys.88.807 |pmid=21594053|pmc=3088472|bibcode=2011ZooK...88....1B |doi-access=free }}</ref>
| subdivision = * [[Adephaga]]
* [[Archostemata]]
* [[Myxophaga]]
* [[Polyphaga]]
* †[[Protocoleoptera]]
''See [[subgroups of the order Coleoptera]]''
}}

'''Beetles''' are [[insect]]s that form the [[Taxonomic rank|order]] '''Coleoptera''' ({{IPAc-en|k|oʊ|l|iː|'|Q|p|t|ɛr|@}}), in the superorder [[Holometabola]]. Their front pair of wings are hardened into wing-cases, [[elytra]], distinguishing them from most other insects. The Coleoptera, with about 400,000 described species, is the largest of all orders, constituting almost 40% of described arthropods and 25% of all known animal species;<ref name="Stork2018">{{cite journal |last1=Stork |first1=Nigel E. |title=How Many Species of Insects and Other Terrestrial Arthropods Are There on Earth? |journal=Annual Review of Entomology |date=7 January 2018 |volume=63 |issue=1 |pages=31–45 |doi=10.1146/annurev-ento-020117-043348|pmid=28938083 |s2cid=23755007 |doi-access=free }}</ref> new species are discovered frequently, with estimates suggesting that there are between 0.9 and 2.1 million total species. Other similarly diverse orders are [[Fly|dipterans]] (flies) and [[hymenoptera]]ns (wasps). 

Found in almost every habitat except the sea and the [[polar region]]s, they interact with their [[ecosystem]]s in several ways: beetles often feed on plants and [[fungi]], break down animal and plant debris, and eat other [[invertebrate]]s. Some species are serious agricultural pests, such as the [[Colorado potato beetle]], while others such as [[Coccinellidae]] (ladybirds or ladybugs) eat [[aphid]]s, [[scale insect]]s, [[thrips]], and other plant-sucking insects that damage crops. Some others also have unusual characteristics, such as [[fireflies]], which use a light-emitting organ for mating and communication purposes.

Beetles typically have a particularly hard [[exoskeleton]] including the [[elytra]], though some such as the [[rove beetles]] have very short elytra while [[blister beetle]]s have softer elytra. The general [[anatomy]] of a beetle is quite uniform and typical of insects, although there are several examples of novelty, such as adaptations in [[water beetle]]s which trap air bubbles under the elytra for use while diving. Beetles are [[holometabola]]ns, which means that they undergo complete [[metamorphosis]], with a series of conspicuous and relatively abrupt changes in body structure between hatching and becoming adult after a relatively immobile [[pupa]]l stage. Some, such as [[stag beetle]]s, have a marked [[sexual dimorphism]], the males possessing enormously enlarged [[Mandible (insect mouthpart)|mandibles]] which they use to fight other males. Many beetles are [[aposematic]], with bright colors and patterns warning of their toxicity, while others are harmless [[Batesian mimics]] of such insects. Many beetles, including those that live in sandy places, have effective [[camouflage]].

Beetles are prominent [[insects in culture|in human culture]], from the [[Scarab (artifact)|sacred scarabs]] of [[ancient Egypt]] to [[beetlewing]] art and use as [[pet]]s or [[insect fighting|fighting insects]] for entertainment and gambling. Many beetle groups are brightly and attractively colored making them objects of collection and decorative displays. Over 300 species are [[entomophagy|used as food]], mostly as [[larva]]e; species widely consumed include [[mealworm]]s and [[rhinoceros beetle]] larvae. However, the major impact of beetles on human life is as agricultural, forestry, and horticultural [[Pest (organism)|pests]]. Serious pest species include the [[boll weevil]] of cotton, the [[Colorado potato beetle]], the [[Brontispa longissima|coconut hispine beetle]], the [[mountain pine beetle]], and many others. Most beetles, however, do not cause economic damage and some, such as numerous species of [[lady beetle]]s, are beneficial by helping to control insect pests. The scientific study of beetles is known as [[coleopterology]].

==Etymology==
[[File:Coleoptera SMNK.jpg|thumb|Coleoptera at the [[State Museum of Natural History, Karlsruhe]], Germany]]

The name of the taxonomic order, Coleoptera, comes from the [[Ancient Greek|Greek]] ''koleopteros'' (κολεόπτερος), given to the group by [[Aristotle]] for their [[elytra]], hardened shield-like forewings, from ''koleos'', sheath, and ''pteron'', wing. The English name beetle comes from the [[Old English]] word ''bitela'', little biter, related to ''bītan'' (to bite),<ref name="Etymology">{{OEtymD|Coleoptera}}</ref><ref name="Etymology_Beetle">{{OEtymD|Beetle}}</ref> leading to [[Middle English]] ''betylle''.<ref name="Merriam_Dictionary">{{cite web |title=Beetle |url=http://www.merriam-webster.com/dictionary/Beetle |publisher=Merriam-Webster Online Dictionary |access-date=20 February 2016}}</ref> Another Old English name for beetle is ''ċeafor'', chafer, used in names such as [[cockchafer]], from the Proto-Germanic *''kebrô'' ("beetle"; compare German ''Käfer'', Dutch ''kever'', Afrikaans ''kewer'').<ref name="Etymology_Chafer">{{OEtymD|Chafer}}</ref>

== Distribution and diversity ==

Beetles are by far the largest order of insects: the roughly 400,000 species make up about 40% of all arthropod species so far described, and about 25% of all animal species.<ref name="Bouchard_et_al_2011"/><ref name="Gilliott">{{cite book |last=Gilliott |first=Cedric |title=Entomology |publisher=Springer-Verlag |date=August 1995 |edition=2 |isbn=978-0-306-44967-3 |url=https://books.google.com/books?id=DrTKxvZq_IcC&pg=PA96 |page=96}}</ref><ref name=insenc>[[#refMcHugh |McHugh (2009)]]</ref><ref name="Rosenzweig_1995">{{Cite book |last1=Rosenzweig |first1=M. L. |title=Species Diversity in Space and Time |publisher=Cambridge University Press |location=Cambridge |isbn=978-0-521-49952-1 |year=1995 |page=2}}</ref><ref name="Hunt_et_al_2007">{{cite journal |author=Hunt, T. |title=A Comprehensive Phylogeny of Beetles Reveals the Evolutionary Origins of a Superradiation |journal=[[Science (journal) |Science]] |volume=318 |issue=5858 |pages=1913–1916 |year=2007 |pmid=18096805 |doi=10.1126/science.1146954 |last2=Bergsten |first2=J. |last3=Levkanicova |first3=Z. |last4=Papadopoulou |first4=A. |last5=John |first5=O. S. |last6=Wild |first6=R. |last7=Hammond |first7=P. M. |last8=Ahrens |first8=D. |last9=Balke |first9=M. |last10=Caterino |first10=M. S. |last11=Gómez-Zurita |first11=J. |last12=Ribera |first12=I |last13=Barraclough |first13=T. G. |last14=Bocakova |first14=M. |last15=Bocak |first15=L |last16=Vogler |first16=A. P. |display-authors=5 |bibcode=2007Sci...318.1913H |s2cid=19392955 }}</ref><ref name="Hammond_1992">{{cite book |editor-last1=Groombridge |editor-first1=Brian |last1=Hammond |first1=Peter |title=Global Biodiversity: Status of the Earth's Living Resources |date=1992 |publisher=Chapman & Hall |location=London |isbn=978-0-412-47240-4 |pages=17–39 |url=https://wedocs.unep.org/bitstream/handle/20.500.11822/7981/globalbiodiversi92wcmc.pdf |chapter=Species Inventory }}</ref> A 2015 study provided four independent estimates of the total number of beetle species, giving a mean estimate of some 1.5&nbsp;million with a "surprisingly narrow range"<ref name=Stork/> spanning all four estimates from a minimum of 0.9 to a maximum of 2.1&nbsp;million beetle species. The four estimates made use of host-specificity relationships (1.5 to 1.9&nbsp;million), ratios with other taxa (0.9 to 1.2&nbsp;million), plant:beetle ratios (1.2 to 1.3), and extrapolations based on body size by year of description (1.7 to 2.1&nbsp;million).<ref name="Stork">{{cite journal |last1=Stork |first1=Nigel E. |last2=McBroom |first2=James |last3=Gely |first3=Claire |last4=Hamilton |first4=Andrew J. |title=New approaches narrow global species estimates for beetles, insects, and terrestrial arthropods |journal=PNAS |date=2015 |volume=116 |issue=24 |pages=7519–7523 |doi=10.1073/pnas.1502408112 |bibcode=2015PNAS..112.7519S |pmid=26034274 |pmc=4475949 |doi-access=free }}</ref><ref>{{cite book |last=Gullan |first=P.J. |author2=Cranston, P.S. |title=The Insects: An Outline of Entomology |url=https://archive.org/details/insectsoutlineen00pjgu |url-access=limited |publisher=John Wiley & Sons |date=2014 |edition=5 |isbn=978-1-4443-3036-6 |page=[https://archive.org/details/insectsoutlineen00pjgu/page/n24 6]}}</ref>

This immense diversity led the evolutionary biologist [[J. B. S. Haldane]] to quip, when some [[theologians]] asked him what could be inferred about the mind of the [[Christian God]] from the works of His Creation, "An inordinate fondness for beetles".<ref name="Hutchinson_1959">{{cite journal |last1=Hutchinson |first1=G. E. |year=1959 |title=Homage to Santa Rosalia or why are there so many kinds of animals? |journal=The American Naturalist |volume=93 |issue=870 |pages=145–159 |doi=10.1086/282070 |jstor=2458768 |bibcode=1959ANat...93..145H |s2cid=26401739 }}</ref>

However, the ranking of beetles as most diverse has been challenged. Multiple studies posit that Diptera (flies) and/or Hymenoptera (sawflies, wasps, ants and bees) may have more species.<ref>{{Cite journal |last1=Hebert |first1=Paul D. N. |last2=Ratnasingham |first2=Sujeevan |last3=Zakharov |first3=Evgeny V. |last4=Telfer |first4=Angela C. |last5=Levesque-Beaudin |first5=Valerie |last6=Milton |first6=Megan A. |last7=Pedersen |first7=Stephanie |last8=Jannetta |first8=Paul |last9=deWaard |first9=Jeremy R. |display-authors=5 |date=2016-09-05 |title=Counting animal species with DNA barcodes: Canadian insects |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |volume=371 |issue=1702 |article-number=20150333 |doi=10.1098/rstb.2015.0333 |pmc=4971185 |pmid=27481785}}</ref><ref>{{Cite journal |last1=Borkent |first1=Art |last2=Brown |first2=Brian V. |last3=Adler |first3=Peter H. |last4=Amorim |first4=Dalton De Souza |last5=Barber |first5=Kevin |last6=Bickel |first6=Daniel |last7=Boucher |first7=Stephanie |last8=Brooks |first8=Scott E. |last9=Burger |first9=John |last10=Burington |first10=Z.L. |last11=Capellari |first11=Renato S. |last12=Costa |first12=Daniel N.R. |last13=Cumming |first13=Jeffrey M. |last14=Curler |first14=Greg |last15=Dick |first15=Carl W. |display-authors=5 |date=2018-03-27 |title=Remarkable fly (Diptera) diversity in a patch of Costa Rican cloud forest: Why inventory is a vital science |url=https://www.mapress.com/zt/article/view/zootaxa.4402.1.3 |journal=Zootaxa |volume=4402 |issue=1 |pages=53–90 |doi=10.11646/zootaxa.4402.1.3 |pmid=29690278 |s2cid=13819313 |hdl=10138/234433 |hdl-access=free }}</ref><ref>{{Cite journal |last1=Forbes |first1=Andrew A. |last2=Bagley |first2=Robin K. |last3=Beer |first3=Marc A. |last4=Hippee |first4=Alaine C. |last5=Widmayer |first5=Heather A. |date=2018-07-12 |title=Quantifying the unquantifiable: why Hymenoptera, not Coleoptera, is the most speciose animal order |journal=BMC Ecology |volume=18 |issue=1 |page=21 |doi=10.1186/s12898-018-0176-x |pmc=6042248 |pmid=30001194 |bibcode=2018BMCE...18...21F |doi-access=free }}</ref>

Beetles are found in nearly all habitats, including freshwater and coastal habitats, wherever vegetative foliage is found, from trees and their bark to flowers, leaves, and underground near roots - even inside plants in galls, in every plant tissue, including dead or decaying ones.<ref>{{cite book |last=Gullan |first=P. J. |author2=Cranston, P. S. |title=The Insects: An Outline of Entomology |url=https://archive.org/details/insectsoutlineen00pjgu |url-access=limited |publisher=John Wiley & Sons |date=2014 |edition=5 |isbn=978-1-4443-3036-6 |page=[https://archive.org/details/insectsoutlineen00pjgu/page/n541 517]}}</ref> Tropical forest canopies have a large and diverse fauna of beetles,<ref>Kirmse S, Adis J, Morawetz W. 2003. Flowering events and beetle diversity in Venezuela. In: Basset Y, Novotny V, Miller SE, Kitching RL, editors. Arthropods of tropical forests: Spatio-temporal dynamics and resource use in the canopy. Cambridge: Cambridge University Press; p. 256–265.</ref> including [[Carabidae]],<ref>{{cite journal |doi=10.1649/0010-065x(2001)055[0297:abonfa]2.0.co;2 |title=Arboreal Beetles of Neotropical Forests:Agra ''Fabricius'', Larval Descriptions with Notes on Natural History and Behaviour (Coleoptera, Carabidae, Lebiini, Agrina) |year=2001 |last1=Arndt |first1=Erik |last2=Kirmse |first2=Susan |last3=Erwin |first3=Terry L. |journal=The Coleopterists Bulletin |volume=55 |issue=3 |pages=297–310 |s2cid=52065045 }}</ref> [[Chrysomelidae]],<ref>{{Cite journal |doi=10.1080/00222933.2018.1548666 |title=Polyphagy and florivory prevail in a leaf-beetle community (Coleoptera: Chrysomelidae) inhabiting the canopy of a tropical lowland rainforest in southern Venezuela |year=2018 |last1=Kirmse |first1=Susan |last2=Chaboo |first2=Caroline S. |journal=Journal of Natural History |volume=52 |issue=41–42 |pages=2677–2721 |bibcode=2018JNatH..52.2677K |s2cid=91732501}}</ref> and [[Scarabaeidae]].<ref>{{Cite journal |doi=10.1649/0010-065X-73.1.149 |title=Composition and Host-Use Patterns of a Scarab Beetle (Coleoptera: Scarabaeidae) Community Inhabiting the Canopy of a Lowland Tropical Rainforest in Southern Venezuela |year=2019 |last1=Kirmse |first1=Susan |last2=Ratcliffe |first2=Brett C. |journal=The Coleopterists Bulletin |volume=73 |page=149 |s2cid=108786139 |url=https://digitalcommons.unl.edu/entomologyfacpub/799}}</ref>

Among the heaviest beetles, whose [[larva]]l stage can attain a mass of at least {{convert |115 |g |oz |abbr=on}} and a length of {{convert |11.5 |cm |in |abbr=on}}, is  the [[goliath beetle]], ''Goliathus goliatus''; in its adult stage it can weigh {{convert |70-100 |g |oz |abbr=on}} and reach up to {{convert |11 |cm |in |abbr=on}} in length.<ref>{{cite web |url=http://www.guinnessworldrecords.com/world-records/heaviest-insect |title=Heaviest insect |publisher=[[Guinness World Records]] |access-date=2017-02-01}}</ref> Adult [[elephant beetle]]s, ''[[Megasoma elephas]]'' and ''[[Megasoma actaeon]]'' often reach {{convert |50 |g |oz |abbr=on}} and {{convert|10|cm|in|abbr=on}}.<ref name=Williams2001>{{cite web |title=Chapter 30 — Largest Insect |url=http://entnemdept.ufl.edu/walker/ufbir/chapters/chapter_30.shtml |author=Williams, David M. |publisher=[[University of Florida]] |date=2001 |work=Book of Insect Records  |archive-url=https://web.archive.org/web/20110718140051/http://entnemdept.ufl.edu/walker/ufbir/chapters/chapter_30.shtml |archive-date=July 18, 2011 }}</ref>

The longest beetle is the [[Hercules beetle]] ''Dynastes hercules'', with a maximum overall length of at least 16.7&nbsp;cm (6.6&nbsp;in) including the very long [[Prothorax |pronotal]] horn. The smallest recorded beetle and the smallest free-living insect ({{as of |2015 |lc=y}}), is the [[featherwing beetle]] ''[[Scydosella musawasensis]]'' which may measure as little as 325&nbsp;[[μm]] in length.<ref>{{cite journal |last=Polilov |first=Alexey |title=How small is the smallest? New record and remeasuring of Scydosella musawasensis Hall, 1999 (Coleoptera, Ptiliidae), the smallest known free-living insect |date=2015 |journal=[[ZooKeys]] |issue=526 |pages=61–64 |doi=10.3897/zookeys.526.6531 |pmid=26487824 |pmc=4607844 |bibcode=2015ZooK..526...61P |doi-access=free }}</ref>

<gallery heights="175px" mode="packed">
File:Titanus giganteus MHNT dos.jpg |[[Titan beetle]], ''Titanus giganteus'', a tropical [[longhorn beetle|longhorn]], one of the largest and heaviest insects in the world
File:Scydosella musawasensis.jpg |''[[Scydosella musawasensis]]'', the smallest known beetle: scale bar (right) is 50 μm.
File:Dynastes hercules ecuatorianus MHNT.jpg |[[Hercules beetle]], ''Dynastes hercules ecuatorianus'', the longest of all beetles
File:Protaetia-cuprea-ignicollis-IZE-257.jpg |Rose chafer, ''[[Protaetia cuprea]]'', feeding on thistle
</gallery>

==Evolution==
=== Late Paleozoic and Triassic ===

[[File:Moravocoleus permianus.jpg |thumb |Fossil and life restoration of ''Moravocoleus permianus'' ([[Tshekardocoleidae]]) from the Early Permian of the Czech Republic, representative of the morphology of early beetles]]

The oldest known beetle is ''[[Coleopsis]]'', from the earliest Permian ([[Asselian]]) of Germany, around 295 million years ago.<ref>{{Cite journal |last1=Kirejtshuk |first1=Alexander G. |last2=Poschmann |first2=Markus |last3=Prokop |first3=Jakub |last4=Garrouste |first4=Romain |last5=Nel |first5=André |date=2014-07-04 |title=Evolution of the elytral venation and structural adaptations in the oldest Palaeozoic beetles (Insecta: Coleoptera: Tshekardocoleidae) |url=http://www.tandfonline.com/doi/abs/10.1080/14772019.2013.821530 |journal=Journal of Systematic Palaeontology |volume=12 |issue=5 |pages=575–600 |doi=10.1080/14772019.2013.821530 |bibcode=2014JSPal..12..575K |s2cid=85163674 |issn=1477-2019 |url-access=subscription}}</ref> Early beetles from the Permian, which are collectively grouped into the "[[Protocoleoptera]]" are thought to have been [[xylophagous]] (wood eating) and [[Woodboring beetle |wood boring]]. Fossils from this time have been found in Siberia and Europe, for instance in the red slate fossil beds of Niedermoschel near Mainz, Germany.<ref>{{cite journal |last=Hörnschemeyer |first=T. |author2=Stapf, H. |title=Die Insektentaphozönose von Niedermoschel (Asselian, unt. Perm; Deutschland) |trans-title=The insect taphocenosis of Niedermoschel (Asselian and Permian; Germany) |journal=Schriften der Alfred-Wegener-Stiftung |language=de |issue=99/8 |page=98}}</ref> Further fossils have been found in Obora, Czech Republic and Tshekarda in the Ural mountains, Russia.<ref>{{cite journal |last=Kukalová |first=J. |year=1969 |title=On the systematic position of the supposed Permian beetles, Tshecardocoleidae, with a description of a new collection from Moravia |journal=Sborník Geologických Věd, Paleontologie |volume=11 |pages=139–161}}</ref> However, there are only a few fossils from North America before the [[middle Permian]], although both Asia and North America had been united to [[Euramerica]]. The first discoveries from North America made in the [[Wellington Formation]] of Oklahoma were published in 2005 and 2008.<ref name="evo">{{cite web |last=Benisch |first=Christoph |year=2010 |title=Phylogeny of the beetles |url=http://www.kerbtier.de/Pages/Themenseiten/enPhylogenie.html#L9 |access-date=March 16, 2011 |work=The beetle fauna of Germany |publisher=Kerbtier}}</ref><ref>{{cite journal |last=Beckemeyer |first=R. J. |author2=Engel, M. S. |year=2008 |title=A second specimen of ''Permocoleus'' (Coleoptera) from the Lower Permian Wellington Formation of Noble County, Oklahoma |url=http://fossilinsects.net/pdfs/beckemeyer_engel_2008_JKansEntSoc_PermocoleusPermOklahoma.pdf |journal=[[Journal of the Kansas Entomological Society]] |volume=81 |issue=1 |pages=4–7 |doi=10.2317/JKES-708.01.1 |archive-url=https://web.archive.org/web/20110718202310/http://fossilinsects.net/pdfs/beckemeyer_engel_2008_JKansEntSoc_PermocoleusPermOklahoma.pdf |archive-date=July 18, 2011 |s2cid=86835593}}</ref> The earliest members of modern beetle lineages appeared during the [[Late Permian]]. In the [[Permian–Triassic extinction event]] at the end of the Permian, most "protocoleopteran" lineages became extinct. Beetle diversity did not recover to pre-extinction levels until the [[Middle Triassic]].<ref name=":1">{{Cite journal |last1=Zhao |first1=Xianye |last2=Yu |first2=Yilun |last3=Clapham |first3=Matthew E |last4=Yan |first4=Evgeny |last5=Chen |first5=Jun |last6=Jarzembowski |first6=Edmund A. |last7=Zhao |first7=Xiangdong |last8=Wang |first8=Bo |date=2021-11-08 |editor-last=Perry |editor-first=George H. |editor2-last=Fikacek |editor2-first=Martin |title=Early evolution of beetles regulated by the end-Permian deforestation |journal=eLife |volume=10 |article-number=e72692 |doi=10.7554/eLife.72692 |pmid=34747694 |pmc=8585485 |doi-access=free }}</ref>

===Jurassic===

[[File:Phylogenetic chart of Coleoptera.svg|thumb|Beetle [[genus|genera]] were mainly [[detritivore]]s in the [[Permian]] and [[Triassic]]. During the [[Jurassic]], [[herbivorous]] and then [[carnivorous]] genera became more common. In the [[Cenozoic]], genera at all three [[trophic level]]s became far more numerous.]]

During the [[Jurassic]] ({{Ma|210|145|mya}}), there was a dramatic increase in the diversity of beetle families,<ref name="evo"/> including the development and growth of carnivorous and herbivorous species. The [[Chrysomeloidea]] diversified around the same time, feeding on a wide array of plant hosts from [[cycad]]s and [[conifer]]s to [[angiosperm]]s.<ref name="insenc186">[[#refMcHugh|McHugh (2009)]], p. 186</ref> Close to the Upper Jurassic, the Cupedidae decreased, but the diversity of the early plant-eating species increased. Most recent plant-eating beetles feed on flowering plants or angiosperms, whose success contributed to a doubling of plant-eating species during the [[Middle Jurassic]]. However, the increase of the number of beetle families during the Cretaceous does not correlate with the increase of the number of angiosperm species.<ref>{{cite journal |last1=Labandeira |first1=C. C. |last2=Sepkoski |first2=J. J. |year=1993 |title=Insect diversity in the fossil record |journal=[[Science (journal)|Science]] |volume=261 |issue=5119 |pages=310–315 |doi=10.1126/science.11536548 |pmid=11536548 |bibcode=1993Sci...261..310L |url=http://129.123.92.202/biol5530/Labandeira_Sepkoski_1993.pdf  |archive-url=https://web.archive.org/web/20120331061227/http://129.123.92.202/biol5530/Labandeira_Sepkoski_1993.pdf |archive-date=March 31, 2012|citeseerx=10.1.1.496.1576 }}</ref> Around the same time, numerous primitive weevils (e.g. [[Curculionoidea]]) and click beetles (e.g. [[Elateroidea]]) appeared. The first jewel beetles (e.g. [[Buprestidae]]) are present, but they remained rare until the Cretaceous.<ref>{{cite journal |author1=Gratshev, Vadim G. |author2=Zherikhin, Vladimir V. |date=October 15, 2003 |title=Insect diversity in the fossil record |journal=Acta Zoologica Cracoviensia |volume=261 |issue=5119 |pages=129–138 |url=http://www.isez.pan.krakow.pl/journals/azc_i/pdf/46(suppl)/15.pdf |bibcode=1993Sci...261..310L |doi=10.1126/science.11536548 |pmid=11536548 |citeseerx=10.1.1.496.1576 |access-date=March 16, 2011 |archive-date=December 29, 2016 |archive-url=https://web.archive.org/web/20161229073633/http://www.isez.pan.krakow.pl/journals/azc_i/pdf/46(suppl)/15.pdf  }}</ref><ref>{{cite journal |author1=Chang, H. |author2=Zhang, F. |author3=Ren, D. |year=2008 |title=A new genus and two new species of fossil elaterids from the Yixian Formation of Western Liaoning, China (Coleoptera: Elateridae) |journal=[[Zootaxa]] |volume=1785 |issue=1 |pages=54–62 |url=http://202.204.209.200/upload/20080609030648.pdf  |archive-url=https://web.archive.org/web/20110704101413/http://202.204.209.200/upload/20080609030648.pdf |archive-date=July 4, 2011|doi=10.11646/zootaxa.1785.1.3 }}</ref><ref>{{cite journal |author1=Alexeev, A. V. |year=1993 |title=Jurassic and Lower Cretaceous Buprestidae (Coleoptera) from Eurasia |journal=[[Paleontological Journal]]|issue=1A |pages=9–34 |url=http://www.zin.ru/Animalia/Coleoptera/pdf/Alexeev%20-%20jurassic%20and%20lc%20buprestidae%2093.pdf |archive-url=https://web.archive.org/web/20100326031216/http://www.zin.ru/Animalia/Coleoptera/pdf/Alexeev%20-%20jurassic%20and%20lc%20buprestidae%2093.pdf |archive-date=2010-03-26 |url-status=live}}</ref> 

There are more than 150 important fossil sites from the Jurassic, the majority in Eastern Europe and North Asia. Outstanding sites include [[Solnhofen]] in Upper [[Bavaria]], Germany,<ref>{{cite journal |author=Ponomarenko, Alexandr G. |year=1985 |title=Fossil insects from the Tithonian 'Solnhofener Plattenkalke' in the Museum of Natural History, Vienna |journal=Annalen des Naturhistorischen Museums in Wien |volume=87 |issue=1 |pages=135–144 |url=http://www.landesmuseum.at/pdf_frei_remote/ANNA_87A_0135-0144.pdf |archive-url=https://web.archive.org/web/20110704203743/http://www.landesmuseum.at/pdf_frei_remote/ANNA_87A_0135-0144.pdf |archive-date=2011-07-04 |url-status=live}}</ref> Karatau in South [[Kazakhstan]],<ref>{{cite journal|title=A new genus of elateriform beetles (Coleoptera, Polyphaga) from the Middle-Late Jurassic of Karatau |journal=[[Paleontological Journal]] |year=2009 |author=Yan, E. V. |volume=43 |issue=1 |pages=78–82 |url=http://fossilinsects.net/pdfs/Yan_2009_PalJ_ElateriformJurassicKaratau.pdf |doi=10.1134/S0031030109010080 |bibcode=2009PalJ...43...78Y |s2cid=84621777  |archive-url=https://web.archive.org/web/20110718202329/http://fossilinsects.net/pdfs/Yan_2009_PalJ_ElateriformJurassicKaratau.pdf |archive-date=July 18, 2011 }}</ref> the Yixian formation in [[Liaoning]], North China,<ref name="liaoning">{{cite journal |title=New ommatids from the Late Jurassic of western Liaoning, China (Coleoptera: Archostemata) |journal=Insect Science |year=2005 |author1=Tan, J.-J. |author2=Ren, D. |author3=Liu, M. |volume=12 |pages=207–216 |url=http://fossilinsects.net/pdfs/tan_etal_2005.pdf |doi=10.1111/j.1005-295X.2005.00026.x |issue=3 |bibcode=2005InsSc..12..207T |s2cid=83733980  |archive-url=https://web.archive.org/web/20110718202354/http://fossilinsects.net/pdfs/tan_etal_2005.pdf |archive-date=July 18, 2011 }}</ref> as well as the Jiulongshan formation and further fossil sites in [[Mongolia]]. In North America there are only a few sites with fossil records of insects from the Jurassic, namely the shell limestone deposits in the Hartford basin, the Deerfield basin and the Newark basin.<ref name="evo"/><ref>{{cite journal |title=New beetles of the family Cupedidae from the Mesozoic of Mongolia. Ommatini, Mesocupedini, Priacmini |journal=[[Paleontological Journal]] |year=1997 |author=Ponomarenko, A. G. |volume=31 |issue=4 |pages=389–399 |url=http://www.palaeoentomolog.ru/Publ/PALJ389.pdf| archive-url=https://web.archive.org/web/20060925135716/http://www.palaeoentomolog.ru/Publ/PALJ389.pdf| archive-date=2006-09-25}}</ref>

===Cretaceous===
The [[Cretaceous]] saw the fragmenting of the southern landmass, with the opening of the southern Atlantic Ocean and the isolation of New Zealand, while South America, Antarctica, and Australia grew more distant.<ref name="insenc186"/> The diversity of Cupedidae and [[Archostemata]] decreased considerably. Predatory ground beetles (Carabidae) and rove beetles (Staphylinidae) began to distribute into different patterns; the [[Carabidae]] predominantly occurred in the warm regions, while the [[Staphylinidae]] and [[click beetle]]s (Elateridae) preferred temperate climates. Likewise, predatory species of [[Cleroidea]] and [[Cucujoidea]] hunted their prey under the bark of trees together with the [[jewel beetle]]s (Buprestidae). The diversity of jewel beetles increased rapidly, as they were the primary consumers of wood,<ref>{{cite journal|title=New Jewel Beetles (Coleoptera: Buprestidae) from the Cretaceous of Russia, Kazakhstan, and Mongolia |journal=Paleontological Journal |year=2009 |volume=43 |issue=3 |pages=277–281 |url=http://fossilinsects.net/pdfs/Alexeev_2009_PalJ_BuprestidaeCretaceousRussiaKazakhstanMongolia.pdf |doi=10.1134/s0031030109030058 |last1=Alexeev |first1=A. V. |bibcode=2009PalJ...43..277A |s2cid=129618839  |archive-url=https://web.archive.org/web/20110718202416/http://fossilinsects.net/pdfs/Alexeev_2009_PalJ_BuprestidaeCretaceousRussiaKazakhstanMongolia.pdf |archive-date=July 18, 2011 }}</ref> while [[longhorn beetle]]s ([[Cerambycidae]]) were rather rare: their diversity increased only towards the end of the Upper Cretaceous.<ref name="evo"/> The first coprophagous beetles are from the Upper Cretaceous<ref>{{cite journal |author1=Chin, K. |author2=Gill, B. D. |title=Dinosaurs, dung beetles, and conifers; participants in a Cretaceous food web |journal=PALAIOS |year=1996 |issue=3 |pages=280–285 |doi=10.2307/3515235 |volume=11|bibcode=1996Palai..11..280C |jstor=3515235 }}</ref> and may have lived on the excrement of herbivorous dinosaurs.<ref>{{cite journal|author1=Arillo, Antonio |author2=Ortuño, Vicente M. |name-list-style=amp |year=2008 |title=Did dinosaurs have any relation with dung-beetles? (The origin of coprophagy) |journal=[[Journal of Natural History]] |volume=42 |issue=19&20 |pages=1405–1408 |doi=10.1080/00222930802105130|bibcode=2008JNatH..42.1405A |s2cid=83643794 }}</ref> The first species where both larvae and adults are adapted to an aquatic lifestyle are found. Whirligig beetles (Gyrinidae) were moderately diverse, although other early beetles (e.g. Dytiscidae) were less, with the most widespread being the species of [[Coptoclavidae]], which preyed on aquatic fly larvae.<ref name="evo"/>
A 2020 review of the palaeoecological interpretations of fossil beetles from Cretaceous ambers has suggested that [[saproxylic]]ity was the most common feeding strategy, with [[fungivorous]] species in particular appearing to dominate.<ref name="amber">{{cite journal|author1=David Peris|author2=Jes Rust|title=Cretaceous beetles (Insecta: Coleoptera) in amber: the palaeoecology of this most diverse group of insects|journal=Zoological Journal of the Linnean Society|year=2020|volume=189|issue=4|pages=1085–1104|url=https://academic.oup.com/zoolinnean/article/189/4/1085/5638889|doi=10.1093/zoolinnean/zlz118|url-access=subscription}}</ref>

Many fossil sites worldwide contain beetles from the Cretaceous. Most are in Europe and Asia and belong to the temperate climate zone during the Cretaceous.<ref name="liaoning"/> Lower Cretaceous sites include the Crato fossil beds in the Araripe basin in the [[Ceará]], North Brazil, as well as overlying Santana formation; the latter was near the equator at that time. In Spain, important sites are near [[Montsec]] and [[Las Hoyas]]. In Australia, the Koonwarra fossil beds of the Korumburra group, [[South Gippsland]], Victoria, are noteworthy. Major sites from the Upper Cretaceous include Kzyl-Dzhar in South Kazakhstan and Arkagala in Russia.<ref name="evo"/>

===Cenozoic===
[[File:Prachtkäfer aus der Grube Messel.JPG|thumb|Fossil [[Buprestidae|buprestid beetle]] from the [[Eocene]] (50 mya) [[Messel pit]], which retains its [[structural color]]<ref>{{cite journal|doi=10.1098/rspb.2011.1677 |pmid=21957131 |title=The original colours of fossil beetles |journal=Proceedings of the Royal Society B: Biological Sciences |volume=279 |issue=1731 |pages=1114–1121 |year=2011 |last1=McNamara |first1=M. E. |last2=Briggs |first2=D. E. G. |last3=Orr |first3=P. J. |last4=Noh |first4=H. |last5=Cao |first5=H.|pmc=3267148 }}</ref>]]
<!--[[File:Baltic amber Coleoptera Scraptiidae.JPG|thumb|[[Eocene]] beetle preserved in [[Baltic amber]]]]-->

Beetle fossils are abundant in the Cenozoic; by the [[Quaternary]] (up to 1.6 mya), fossil species are identical to living ones, while from the [[Late Miocene]] (5.7 mya) the fossils are still so close to modern forms that they are most likely the ancestors of living species. The [[Quaternary glaciation|large oscillations in climate]] during the Quaternary caused beetles to change their geographic distributions so much that current location gives little clue to the biogeographical history of a species. It is evident that geographic isolation of populations must often have been broken as insects moved under the influence of changing climate, causing mixing of gene pools, rapid evolution, and extinctions, especially in middle latitudes.<ref name="Coope">{{cite journal |last1=Coope |first1=G. R. |title=Late Cenozoic Fossil Coleoptera: Evolution, Biogeography, and Ecology |journal=Annual Review of Ecology and Systematics |date=1979 |volume=10 |issue=1 |pages=246–267 |doi=10.1146/annurev.es.10.110179.001335 |jstor=2096792|bibcode=1979AnRES..10..247C }}</ref>

==Phylogeny==
The very large number of beetle species poses special problems for [[Linnaean taxonomy|classification]]. Some families contain tens of thousands of species, and need to be divided into subfamilies and tribes. [[Polyphaga]] is the largest suborder, containing more than 300,000 described species in more than 170 families, including [[rove beetle]]s (Staphylinidae), scarab beetles ([[Scarabaeidae]]), [[blister beetle]]s (Meloidae), [[stag beetle]]s (Lucanidae) and true weevils ([[Curculionidae]]).<ref name="Hunt_et_al_2007"/><ref name="TOLweb_1995">{{cite web |url=http://tolweb.org/Polyphaga/8870 |title=Polyphaga |last1=Maddison |first1=D. R. |year=1995 |work=Tree of Life web project |access-date=27 February 2016}}</ref> These polyphagan beetle groups can be identified by the presence of cervical [[sclerite]]s (hardened parts of the head used as points of attachment for muscles) absent in the other suborders.<ref>{{cite book |author1=Beutel, R. G. |author2=Lawrence, J. F. |editor1=Kristensen, N. P. |editor2=Beutel, R. G. |date=2005 |title=Handbook of Zoology, Band 4: Arthropoda, 2: Insecta, Coleoptera, Beetles. Volume 1: Morphology and Systematics (Archostemata, Adephaga, Myxophaga, Polyphaga partim) |chapter=4. Coleoptera (Morphology) |page=23 |publisher=Walter de Gruyter |isbn=978-3-11-017130-3}}</ref>
[[Adephaga]] contains about 10 families of largely predatory beetles, includes [[ground beetle]]s (Carabidae), water beetles ([[Dytiscidae]]) and [[whirligig beetle]]s (Gyrinidae). In these insects, the [[testes]] are tubular and the first abdominal sternum (a plate of the [[exoskeleton]]) is divided by the hind [[Arthropod leg|coxae]] (the basal joints of the beetle's legs).<ref>{{cite book |author1=Beutel, R. G. |author2=Ribera, I. |editor1=Kristensen, N. P. |editor2=Beutel, R. G. |date=2005 |title=Handbook of Zoology, Band 4: Arthropoda, 2: Insecta, Coleoptera, Beetles. Volume 1: Morphology and Systematics (Archostemata, Adephaga, Myxophaga, Polyphaga partim) |chapter=7. Adephaga Schellenberg, 1806 |page=54 |publisher=Walter de Gruyter |isbn=978-3-11-017130-3}}</ref>
[[Archostemata]] contains four families of mainly wood-eating beetles, including [[reticulated beetle]]s (Cupedidae) and the [[telephone-pole beetle]].<ref>{{cite web |url=http://bugguide.net/node/view/40603 |title=Suborder Archostemata – Reticulated and Telephone-pole Beetles |publisher=BugGuide |date=2006 |access-date=2017-01-26}}</ref>
The Archostemata have an exposed plate called the metatrochantin in front of the basal segment or coxa of the hind leg.<ref name="ausbeetle"/> [[Myxophaga]] contains about 65 described species in four families, mostly very small, including [[Hydroscaphidae]] and the genus ''[[Sphaerius]]''.<ref>{{Cite journal |last=Mesaros |first=Gabor |title=Sphaeriusidae (Coleoptera, Myxophaga): A new beetle family to the fauna of Serbia |url=http://scindeks.ceon.rs/Article.aspx?artid=1820-95211306071M |journal=Bulletin of the Natural History Museum |issue=6 |pages=71–74 |doi=10.5937/bnhmb1306071m|year=2013 |doi-access=free }}</ref> The myxophagan beetles are small and mostly alga-feeders. Their mouthparts are characteristic in lacking [[Maxilla (arthropod mouthpart)#Hexapoda|galeae]] and having a mobile tooth on their left mandible.<ref>{{cite book |title=Handbook of Zoology. Volume 4. Part 38. Arthropoda. Morphology and Systematics (Archostemata, Adephaga, Myxophaga, Polyphaga partim) |last2=Leschen |first2=Richard |publisher=Walter de Gruyter |year=2005 |page=43 |first1=Rolf G.|last1=Beutel }}</ref>

The consistency of beetle [[Morphology (biology)|morphology]], in particular their possession of [[elytra]], has long suggested that Coleoptera is [[monophyletic]], though there have been doubts about the arrangement of the [[Taxonomic rank|suborders]], namely the [[Adephaga]], [[Archostemata]], [[Myxophaga]] and [[Polyphaga]] within that [[clade]].<ref name=whiting>{{cite journal|author=Whiting, Michael F. |year=2002 |title=Phylogeny of the holometabolous insect orders: molecular evidence |journal=[[Zoologica Scripta]] |volume=31 |issue=1 |pages=3–15 |doi=10.1046/j.0300-3256.2001.00093.x|s2cid=45544978 }}</ref><ref name="insenc186"/><ref name="Beutel">{{cite journal |title=Phylogenetic relationships of the suborders of Coleoptera (Insecta) |journal=[[Cladistics (journal)|Cladistics]] |first=R. |last=Beutel |author2=Haas, F. |volume=16 |pages=103–141 |doi=10.1111/j.1096-0031.2000.tb00350.x |year=2000|issue=1 |pmid=34902922 |s2cid=56131113 |doi-access=free }}</ref><ref name="Kukalová">{{cite journal |title=Evolution of the hind wing in Coleoptera |journal=[[Canadian Entomologist]] |year=1993 |last=Kukalová-Peck |first=J. |author2=Lawrence, J. F. |volume=125 |issue=2 |pages=181–258 |doi=10.4039/Ent125181-2|s2cid=52888506 }}</ref><ref>{{cite journal |last1=Maddison |first1=D. R. |last2=Moore |first2=W. |last3=Baker |first3=M. D. |last4=Ellis |first4=T. M. |last5=Ober |first5=K. A. |last6=Cannone |first6=J. J. |last7=Gutell |first7=R. R. |title=Monophyly of terrestrial adephagan beetles as indicated by three nuclear genes (Coleoptera: Carabidae and Trachypachidae) |journal=Zoologica Scripta |date=2009 |volume=38 |issue=1 |pages=43–62 |doi=10.1111/j.1463-6409.2008.00359.x |pmid=19789725 |pmc=2752903}}</ref> The twisted-wing parasites, [[Strepsiptera]], are thought to be a sister group to the beetles, having split from them in the [[Early Permian]].<ref name="Kukalová"/><ref>{{cite web |url=http://tolweb.org/coleoptera |title=Coleoptera. Beetle |access-date=March 18, 2011 |last=Maddison |first=David R. |date=September 11, 2000|work=[[Tree of Life Web Project]] |publisher=tolweb.org}}</ref><ref>{{cite journal |author1=Niehuis, Oliver |author2=Hartig, Gerrit |author3=Grath, Sonja |display-authors=etal|title=Genomic and Morphological Evidence Converge to Resolve the Enigma of Strepsiptera |doi=10.1016/j.cub.2012.05.018 |year=2012 | volume=22 |issue=14|journal=Current Biology |pages=1309–1313 |pmid=22704986|doi-access=free |bibcode=2012CBio...22.1309N }}</ref><ref name="McKenna2015"/>

Molecular phylogenetic analysis confirms that the Coleoptera are monophyletic. Duane McKenna et al. (2015) used eight nuclear genes for 367 species from 172 of 183 Coleopteran families. They split the Adephaga into 2 clades, Hydradephaga and Geadephaga, broke up the Cucujoidea into 3 clades, and placed the Lymexyloidea within the Tenebrionoidea. The Polyphaga appear to date from the Triassic. Most extant beetle families appear to have arisen in the Cretaceous.<ref name="McKenna2015">{{cite journal|last1=McKenna |first1=Duane D. |last2=Wild |first2=Alexander L. |display-authors=etal |title=The beetle tree of life reveals that Coleoptera survived end-Permian mass extinction to diversify during the Cretaceous terrestrial revolution |journal=Systematic Entomology |date=2015 |volume=40 |issue=4 |pages=835–880 |doi=10.1111/syen.12132|bibcode=2015SysEn..40..835M |doi-access=free |hdl=10057/11540 |hdl-access=free }}</ref> The [[cladogram]] is based on McKenna (2015).<ref name="McKenna2015"/> The number of species in each group (mainly superfamilies) is shown in parentheses, and boldface if over 10,000.<ref name=Hunt2007/> English common names are given where possible. Dates of origin of major groups are shown in italics in millions of years ago (mya).<ref name="Hunt2007">{{cite journal |last1=Hunt |first1=Toby |display-authors=etal |title=A Comprehensive Phylogeny of Beetles Reveals the Evolutionary Origins of a Superradiation |journal=[[Science (journal)|Science]] |year=2007 |volume=318 |issue=5858 |pages=1913–19116 |doi=10.1126/science.1146954 |pmid=18096805|bibcode=2007Sci...318.1913H |s2cid=19392955 }}</ref>

{{clade|style=font-size:85%;line-height:85%
|label1='''Coleoptera''' |sublabel1=''285 mya''
|1={{clade
 |1={{clade
    |sublabel1=''240 mya''
    |1={{clade
       |sublabel1=''160 mya''
       |1=[[Archostemata]] (40) [[File:Archostemata Tenomerga mucida01 rotated.jpg|80px]]
       |sublabel2=''220 mya''
       |2=[[Myxophaga]] (94) [[File:Sphaerius.acaroides.Reitter.tafel64 (rotated).jpg|50px]]
       }}
     |label2=[[Adephaga]] |sublabel2=''200 mya''
     |2={{clade
          |1=[[Hydradephaga]] (5,560) e.g. [[Dytiscidae]] (diving beetles) [[File:Dytiscus marginalis Linné, 1758 female.jpg|70px]]
          |2=[[Geadephaga]] ('''35,000''') e.g. [[Carabidae]] (ground beetles) [[File:Bembidion_fluviatile_transparent.png|70px]]
        }}
      }}
       |label2=[[Polyphaga]] |sublabel2=''225 mya''
       |2={{clade
          |sublabel1=''200 mya''
          |1=[[Scirtoidea]] (800) + [[Derodontoidea]] (29) [[File:Clambus punctulum (Beck, 1817) (12924039694).png|60px]]
          |2={{clade
             |1={{clade
                |sublabel1=''195 mya''
                |1=[[Staphylinoidea]] ('''48,000''', rove beetles and allies) [[File:Cordalia tsavoana Pace, 2008 (2912937616).jpg|70px]]
                |2={{clade
                   |sublabel1=''145 mya''
                   |1=[[Scarabaeoidea]] ('''35,000''', scarabs, stag beetles, etc.) [[File:Mimela splendens left facing.jpg|70px]]
                   |2={{clade
                      |1=[[Hydrophiloidea]] (2,800, water scavenger beetles) [[File:Hydrophilus piceus (Linné, 1758) female (4035156238).jpg|70px]]
                      |2=[[Histeroidea]] (3,800, clown beetles) [[File:Hister quadrimaculatus Linnaeus, 1758.png|60px]]
                      }}
                   }}
                }}
             |2={{clade
                   |label1=[[Elateriformia]] |sublabel1=''190 mya''
                   |1={{clade 
                      |1=[[Nosodendridae]] (70) [[File:COLE_Nosodendridae_Nosodendron_zealandicum_(cropped).png|60px]]
                      |2={{clade
                         |1=[[Dascilloidea]] (180) [[File:Dascillus cervinus (Linné, 1758) (5598492362).jpg|60px]]
                         |2={{clade
                            |1=[[Buprestoidea]] ('''14,000''', jewel beetles) [[File:Pseudactenodes_schmidti_(transparent).png|70px]]
                            |2={{clade
                               |1=[[Byrrhoidea]] (400, pill and turtle beetles, etc.) [[File:Chaetophora.spinosa.-.calwer.16.17.jpg|50px]]
                               |2=[[Elateroidea]] ('''23,000''', click and soldier beetles, fireflies) [[File:COLE Elateridae Thoramus wakefieldi (cropped).png|70px]]        }}
                            }}
                         }}
                      }}
                    |sublabel2=''190 mya''
                    |2={{clade
                        |1={{clade
                           |1=[[Bostrichoidea]] (3150, deathwatch, powderpost and skin beetles) [[File:Dermestes lardarius Linné, 1758 (28195712552).png|60px]]
                           |label2=[[Cucujiformia]]
                           |2={{clade
                              |1=[[Coccinellidae|Coccinelloidea]] (6,000, ladybirds or lady beetles) [[File:Coccinella.quinquepunctata.jacobs24.jpg|50px]]
                              |2={{clade
                                 |sublabel1=''180 mya''
                                 |1=[[Tenebrionoidea]] ('''35,000''', leaf/flower beetles, etc.) and [[Lymexyloidea]] [[File:Tribolium.castaneum.jpg|70px]]
                                 |2={{clade
                                    |1=[[Cleroidea]] (9,900, checkered beetles and allies) [[File:Tilloidea_unifasciata_(Fabricius,_1787)_(transparent).png|70px]]
                                    |2={{clade
                            |1=[[Cucujoidea]] (8,000) [[File:Cucujus cinnaberinus habitus rotated.jpg|70px]]
                            |label2=[[Phytophaga]] |sublabel2=''170 mya''
                            |2={{clade
                               |label1=[[Chrysomeloidea]]
                               |1={{clade
                                  |1=[[Chrysomelidae]] ('''35,000''', leaf beetles) [[File:Mesoplatys cincta (Olivier, 1790) (8245535128).png|70px]]
                                  |2=[[Cerambycidae]] ('''25,000''', longhorn beetles) [[File:Anaglyptus mysticus transparent.png|70px]]
                                  }}
                               |2=[[Curculionoidea]] ('''97,000''', weevils) [[File:Curculio glandium Marsham, 1802 female (8112399337).png|70px]]
                               }}
                            }}
                         }}
                      }}
                   }}
                }}
             }}
          }}
       }}
    }}
  }}
}}

==External morphology==
[[File:Melolontha_melolontha_insect_morphology.jpg|300px|thumb|right|Beetle body structure, using [[cockchafer]].
A: head, B: thorax, C: abdomen.
1: antenna, 2: compound eye, 3: femur, 4: elytron (wing cover), 5: tibia, 6: tarsus, 7: claws, 8: mouthparts, 9: prothorax, 10: mesothorax, 11: metathorax, 12: abdominal sternites, 13: pygidium.]]

Beetles are generally characterized by a particularly hard [[exoskeleton]] and hard forewings ([[elytra]]) not usable for flying. Almost all beetles have mandibles that move in a horizontal plane. The mouthparts are rarely suctorial, though they are sometimes reduced; the maxillae always bear palps. The antennae usually have 11 or fewer segments, except in some groups like the Cerambycidae (longhorn beetles) and the Rhipiceridae (cicada parasite beetles). The coxae of the legs are usually located recessed within a coxal cavity. The genitalic structures are telescoped into the last abdominal segment in all extant beetles. Beetle larvae can often be confused with those of other holometabolan groups.<ref name="ausbeetle">{{cite book |title=Australian Beetles. Morphology, Classification and Keys |year=2013 |last2=Ślipiński |first2=Adam |publisher=CSIRO |isbn=978-0-643-09728-5 |first1=John F. |last1=Lawrence |pages=1–16}}</ref> The beetle's exoskeleton is made up of numerous plates, called [[sclerite]]s, separated by thin sutures. This design provides armored defenses while maintaining flexibility. The general [[anatomy]] of a beetle is quite uniform, although specific organs and [[appendage]]s vary greatly in appearance and function between the many families in the order. Like all insects, beetles' bodies are divided into three sections: the head, the thorax, and the abdomen.<ref name=insenc/> Because there are so many species, identification is quite difficult, and relies on attributes including the shape of the antennae, the [[tarsal formula]]e{{efn|These count fore, mid, and hind leg tarsal segments, such as 5-5-4.}} and shapes of these small segments on the legs, the mouthparts, and the ventral plates (sterna, pleura, coxae). In many species accurate identification can only be made by examination of the unique male genitalic structures.<ref>{{cite web| title=Introduction to the Identification of Beetles (Coleoptera)| url=http://entnemdept.ufl.edu/choate/beetles.pdf| publisher=University of Florida| access-date=15 March 2017}}{{Dead link|date=September 2025 |bot=InternetArchiveBot }}</ref>

===Head===
[[File:Head of the Weaver Beetle (Lamia textor).jpg|left|thumb|Front view of the head of ''[[Lamia textor]]'']]

The head, having mouthparts projecting forward or sometimes downturned, is usually heavily [[Sclerotin|sclerotized]] and is sometimes very large.<ref name="Gilliott"/> The eyes are [[compound eye|compound]] and may display remarkable adaptability, as in the case of the aquatic whirligig beetles ([[Gyrinidae]]), where they are split to allow a view both above and below the waterline. A few [[Longhorn beetle]]s ([[Cerambycidae]]) and weevils as well as some fireflies ([[Rhagophthalmidae]]) <ref name="Lau">{{ cite journal|author1=Lau T.F.S.| author2=Meyer-Rochow V.B.| title=Sexual dimorphism in the compound eye of ''Rhagophthalmus ohbai'' (Coleoptera; Rhagophthalmidae): I. Morphology and ultrastructure| date=2006| journal= Journal of Asia-Pacific Entomology| volume=9| issue=1| pages=19–30| doi=10.1016/S1226-8615(08)60271-X| bibcode=2006JAsPE...9...19L}}</ref> have divided eyes, while many have eyes that are notched, and a few have [[ocelli]], small, simple [[eye]]s usually farther back on the head (on the [[Vertex (anatomy)|vertex]]); these are more common in larvae than in adults.<ref name='BeetlesAustralia'>{{cite book |author1=Hangay, G. |author2=Zborowski, P.|title=A Guide to the Beetles of Australia |url=https://archive.org/details/guidetobeetlesau00hang |url-access=limited |date=2010 |publisher=CSIRO |page=[https://archive.org/details/guidetobeetlesau00hang/page/n245 10]|isbn=978-0-643-09487-1}}</ref> The anatomical organization of the compound eyes may be modified and depends on whether a species is primarily crepuscular, or diurnally or nocturnally active.<ref name='beetles'>{{cite journal| author1= Gokan N.| author2= Meyer-Rochow V.B.|title=Morphological comparisons of compound eyes in Scarabaeoidea (Coleoptera) related to the beetles' daily activity maxima and phylogenetic positions| date=2000|journal=Journal of Agricultural Science (Tokyo Nogyo Daigaku)| volume=45| issue= 1|pages= 15–61}}</ref> Ocelli are found in the adult carpet beetle (as a single central ocellus in [[Dermestidae]]), some rove beetles ([[Omaliinae]]), and the [[Derodontidae]].<ref name='BeetlesAustralia'/>

[[File:Polyphylla fullo up.jpg|thumb|''[[Polyphylla fullo]]'' has distinctive fan-like [[antenna (biology)|antennae]], one of several distinct forms for the appendages among beetles.|left]]

Beetle [[antenna (biology)|antennae]] are primarily organs of sensory perception and can detect motion, odor and chemical substances,<ref name='Antennae'>{{cite web |url=http://www.kerbtier.de/Pages/Themenseiten/enKoerperbau.html#Fuehler |title=3. Antennae, Beetle morphology |last1=Benisch |first1=Christoph |date=2007 |publisher=Kerbtier.de (Beetle fauna of Germany) |access-date=2017-03-14}}</ref> but may also be used to physically feel a beetle's environment. Beetle families may use antennae in different ways. For example, when moving quickly, tiger beetles may not be able to see very well and instead hold their antennae rigidly in front of them in order to avoid obstacles.<ref>{{cite journal |doi=10.1098/rspb.2013.3072 |pmid=24500171 |title=Static antennae act as locomotory guides that compensate for visual motion blur in a diurnal, keen-eyed predator |journal=Proceedings of the Royal Society B: Biological Sciences |volume=281 |issue=1779 |article-number=20133072 |year=2014 |last1=Zurek |first1=D.B. |last2=Gilbert |first2=C. |pmc=3924084 }}</ref>
Certain Cerambycidae use antennae to balance, and blister beetles may use them for grasping. Some aquatic beetle species may use antennae for gathering air and passing it under the body whilst submerged. Equally, some families use antennae during mating, and a few species use them for defense. In the cerambycid ''[[Onychocerus albitarsis]]'', the antennae have venom injecting structures used in defense, which is unique among [[arthropod]]s.<ref>{{cite journal|doi=10.1007/s00114-007-0316-1|pmid=18004534|title=Convergent evolution in the antennae of a cerambycid beetle, ''Onychocerus albitarsis'', and the sting of a scorpion|journal=Naturwissenschaften|volume=95|issue=3|pages=257–61|year=2007|last1=Berkov|first1=Amy|last2=Rodríguez|first2=Nelson|last3=Centeno|first3=Pedro|bibcode=2008NW.....95..257B|s2cid=30226487}}</ref> Antennae vary greatly in form, sometimes between the sexes, but are often similar within any given family. Antennae may be [[wikt:clavate|clubbed]], [[wikt:filiform|threadlike]], [[wikt:geniculate|angled]], [[wikt:moniliform|shaped like a string of beads]], [[wikt:pectinate|comb-like]] (either on one side or both, bipectinate), or [[wikt:serrate|toothed]]. The physical variation of antennae is important for the identification of many beetle groups. The Curculionidae have elbowed or geniculate antennae. Feather like flabellate antennae are a restricted form found in the Rhipiceridae and a few other families. The Silphidae have a capitate antennae with a spherical head at the tip. The Scarabaeidae typically have lamellate antennae with the terminal segments extended into long flat structures stacked together. The Carabidae typically have thread-like antennae. The antennae arises between the eye and the mandibles and in the Tenebrionidae, the antennae rise in front of a notch that breaks the usually circular outline of the compound eye. They are segmented and usually consist of 11 parts, the first part is called the scape and the second part is the pedicel. The other segments are jointly called the flagellum.<ref name='Antennae'/><ref>{{cite web |url=http://bugs.bio.usyd.edu.au/learning/resources/Entomology/externalMorphology/antennaTypes.html |title=Antennae Types |publisher=University of Sydney |access-date=2017-01-26 |archive-date=February 22, 2018 |archive-url=https://web.archive.org/web/20180222221339/http://bugs.bio.usyd.edu.au/learning/resources/Entomology/externalMorphology/antennaTypes.html  }}</ref><ref>{{cite book |title=American Beetles, Volume I: Archostemata, Myxophaga, Adephaga, Polyphaga: Staphyliniformia |author1= Arnett, R. H. Jr.|author2=Thomas, M. C. |date=2001 |publisher=CRC Press |isbn=978-1-4822-7432-5 |pages=3–7}}</ref>

Beetles have [[Insect mouthparts|mouthparts]] like those of [[grasshopper]]s. The [[mandible (insect)|mandibles]] appear as large pincers on the front of some beetles. The mandibles are a pair of hard, often tooth-like structures that move horizontally to grasp, crush, or cut food or enemies (see [[#Anti-predator adaptations|defence]], below). Two pairs of finger-like appendages, the maxillary and labial palpi, are found around the mouth in most beetles, serving to move food into the mouth. In many species, the mandibles are sexually dimorphic, with those of the males enlarged enormously compared with those of females of the same species.<ref name="Gilliott"/>

===Thorax===

The thorax is [[segmentation (biology)|segmented]] into the two discernible parts, the pro- and pterothorax. The pterothorax is the fused meso- and metathorax, which are commonly separated in other insect species, although flexibly articulate from the prothorax. When viewed from below, the thorax is that part from which all three pairs of legs and both pairs of wings arise. The abdomen is everything posterior to the thorax.<ref name=insenc/> When viewed from above, most beetles appear to have three clear sections, but this is deceptive: on the beetle's upper surface, the middle section is a hard plate called the [[pronotum]], which is only the front part of the thorax; the back part of the thorax is concealed by the beetle's [[insect wing|wings]].<ref>Kusinitz, M. (2021). Beetles. In K. H. Nemeh & J. L. Longe (Eds.), ''The Gale Encyclopedia of Science'' (6th ed., Vol. 1). Gale. 531-536. Gale Document Number: CX8124400293</ref>

[[File:Acilius sulcatus.gemeiner furchenschwimmer.jpg|thumb|''[[Acilius sulcatus]]'', a diving beetle with hind legs adapted as [[Animal locomotion#Swimming|swimming]] limbs]]

===Legs===
The multisegmented [[arthropod leg|legs]] end in two to five small segments called tarsi. Like many other insect orders, beetles have claws, usually one pair, on the end of the last tarsal segment of each leg. While most beetles use their legs for walking, legs have been variously adapted for other uses. Aquatic beetles including the [[Dytiscidae|Dytiscidae (diving beetles)]], [[Haliplidae]], and many species of [[Hydrophilidae]], the legs, often the last pair, are modified for swimming, typically with rows of long hairs. Male diving beetles have suctorial cups on their forelegs that they use to grasp females.<ref>{{Cite journal |last1=Green |first1=Kristina Karlsson |last2=Kovalev |first2=Alexander |last3=Svensson |first3=Erik I. |last4=Gorb |first4=Stanislav N. |date=2013 |title=Male clasping ability, female polymorphism and sexual conflict: fine-scale elytral morphology as a sexually antagonistic adaptation in female diving beetles |journal=Journal of the Royal Society Interface |volume=10 |issue=86 |article-number=20130409 |doi=10.1098/rsif.2013.0409 |pmc=3730688 |pmid=23825114}}</ref> Other beetles have [[fossorial]] legs widened and often spined for digging. Species with such adaptations are found among the scarabs, ground beetles, and [[clown beetle]]s ([[Histeridae]]). The hind legs of some beetles, such as [[flea beetle]]s (within Chrysomelidae) and flea weevils (within Curculionidae), have enlarged femurs that help them leap.<ref>{{cite web |author1=Burkness, S. |author2=Hahn, J. |date=2007 |title=Flea beetles in home gardens |url=http://www.extension.umn.edu/garden/insects/find/flea-beetles/ |access-date=2017-01-26 |publisher=[[University of Minnesota Extension]]}}</ref>

===Wings===
[[File: Soldier Beetle Trichodes alvearius taking off from Knapweed (cropped).jpg|thumb|Checkered beetle ''[[Trichodes alvearius]]'' taking off, showing the hard elytra (forewings adapted as wing-cases) held stiffly away from the flight wings|left]]

The forewings of beetles are not used for [[insect flight|flight]], but form elytra which cover the hind part of the body and protect the hindwings. The elytra are usually hard shell-like structures which must be raised to allow the hindwings to move for flight.<ref name="Carpenter"/> However, in the soldier beetles ([[Cantharidae]]), the elytra are soft, earning this family the name of leatherwings.<ref>{{Citation |title=Leatherwing (Soldier) Beetles |author1=Philips, Chris |author2=Fread, Elizabeth |author3=Kuhar, Tom |access-date=14 March 2017 |url=http://pubs.ext.vt.edu/ENTO/ENTO-53/ENTO-53-pdf.pdf |archive-url=https://web.archive.org/web/20161130002157/http://www.pubs.ext.vt.edu/ENTO/ENTO-53/ENTO-53-pdf.pdf |archive-date=November 30, 2016  }}</ref> Other soft wing beetles include the [[net-winged beetle]] ''[[Calopteron discrepans]]'', which has brittle wings that rupture easily in order to release chemicals for defense.<ref>{{cite web |url=http://entomology.ifas.ufl.edu/creatures/misc/beetles/banded_net-winged_beetle.htm |title=Calopteron discrepans (Newman) (Insecta: Coleoptera: Lycidae) |author1=Donald W. Hall |author2=Marc A. Branham |date=2016 |publisher=[[University of Florida]] |access-date=2017-03-15}}</ref>

Beetles' flight wings are crossed with veins and are folded after landing, often along these veins, and stored below the elytra. A fold (''jugum'') of the membrane at the base of each wing is characteristic.<ref name="Carpenter">{{cite book |title=Insects, their structure and life |first=George Herbert |last=Carpenter |year=1899}}</ref> Some beetles have lost the ability to fly. These include some ground beetles (Carabidae) and some true weevils (Curculionidae), as well as desert- and cave-dwelling species of other families. Many have the two elytra fused together, forming a solid shield over the abdomen. In a few families, both the ability to fly and the elytra have been lost, as in the [[glow-worm]]s ([[Phengodidae]]), where the females [[Larviform female|resemble larvae]] throughout their lives.<ref>{{cite web |url=http://delta-intkey.com/elateria/www/phenmplf.htm |title=''Elateriformia'' (Coleoptera): descriptions, illustrations, identification, and information retrieval for families and subfamilies |author1=Lawrence, J. F. |author2=Hastings, A. M. |author3=Dallwitz, M. J. |author4=Paine, T. A. |author5=Zurcher, E. J. |date=2005 |access-date=2017-01-26}}</ref> The presence of elytra and wings does not always indicate that the beetle will fly. For example, the [[tansy beetle]] walks between habitats despite being physically capable of flight.<ref>{{cite journal |author1=Beenen, R |author2=Winkelman, J. K. |date=2001 |title=Aantekeningen over Chrysomelidae in Nederland 5 |journal=Entomologische Berichten |language=nl |volume=61 |pages=63–67}}</ref>

===Abdomen===
The [[Abdomen#Arthropoda|abdomen]] is the section behind the metathorax, made up of a series of rings, each with a hole for breathing and respiration, called a [[Spiracle (arthropods)|spiracle]], composing three different segmented sclerites: the tergum, pleura, and the sternum. The tergum in almost all species is membranous, or usually soft and concealed by the wings and elytra when not in flight. The pleura are usually small or hidden in some species, with each pleuron having a single spiracle. The sternum is the most widely visible part of the abdomen, being a more or less sclerotized segment. The abdomen itself does not have any appendages, but some (for example, [[Mordellidae]]) have articulating sternal lobes.<ref name="American">{{cite book |last1=Arnett|first1=Ross H. Jr |last2=Thomas |first2=Michael C. |title=American Beetles, Volume I: Archostemata, Myxophaga, Adephaga, Polyphaga: Staphyliniformia |url=https://books.google.com/books?id=bJjSBQAAQBAJ&pg=PA8 |year=2000 |publisher=CRC Press |isbn=978-1-4822-7432-5 |page=8}}</ref>

==Anatomy and physiology==<!--or, Body systems-->
[[File:Internal morphology of Coleoptera.svg|upright=1.7<!--diagram with small captions-->|thumb|A beetle's body systems]]

===Digestive system===
The [[Digestion|digestive system]] of beetles is primarily adapted for a herbivorous diet. Digestion takes place mostly in the anterior [[midgut]], although in predatory groups like the [[Carabidae]], most digestion occurs in the crop by means of midgut enzymes. In the [[Elateridae]], the larvae are liquid feeders that extraorally digest their food by secreting enzymes.<ref name=insenc/> The alimentary canal basically consists of a short, narrow [[pharynx]], a widened expansion, the crop, and a poorly developed [[gizzard]]. This is followed by the midgut, that varies in dimensions between species, with a large amount of [[cecum]], and the hindgut, with varying lengths. There are typically four to six [[Malpighian tubule]]s.<ref name="Gilliott"/>

===Nervous system===
The [[nervous system]] in beetles contains all the types found in insects, varying between different species, from three thoracic and seven or eight abdominal ganglia which can be distinguished to that in which all the thoracic and abdominal ganglia are fused to form a composite structure.<ref name=insenc/>

===Respiratory system===
[[File:DytiscusSpiracles.png|thumb|''[[Dytiscus]]'' [[Spiracle (arthropods)|spiracle]]s (right) on upper side of abdomen, normally covered by the elytra, are in contact with an air bubble when the beetle dives.|left|175x175px]]

Like most insects, beetles inhale air, for the [[oxygen]] it contains, and exhale [[carbon dioxide]], via a [[invertebrate trachea|tracheal system]]. Air enters the body through [[Spiracle (arthropods)|spiracle]]s, and circulates within the haemocoel in a system of [[Invertebrate trachea|tracheae]] and tracheoles, through whose walls the gases can diffuse.<ref name=insenc/>

Diving beetles, such as the [[Dytiscidae]], carry a bubble of air with them when they dive. Such a bubble may be contained under the elytra or against the body by specialized [[hydrophobic]] hairs. The bubble covers at least some of the spiracles, permitting air to enter the tracheae.<ref name=insenc/> The function of the bubble is not only to contain a store of air but to act as a [[Gill#Plastron|physical gill]]. The air that it traps is in contact with oxygenated water, so as the animal's consumption depletes the oxygen in the bubble, more oxygen can diffuse in to replenish it.<ref>{{cite journal|doi=10.1242/jeb.070276 |pmid=23255190 |title=Physical gills in diving insects and spiders: Theory and experiment |journal=The Journal of Experimental Biology |volume=216 |issue=2 |pages=164–70 |year=2012 |last1=Seymour |first1=Roger S. |last2=Matthews |first2=Philip G. D. |doi-access=free }}</ref> Carbon dioxide is more soluble in water than either oxygen or nitrogen, so it readily diffuses out faster than in. Nitrogen is the most plentiful gas in the bubble, and the least soluble, so it constitutes a relatively static component of the bubble and acts as a stable medium for respiratory gases to accumulate in and pass through. Occasional visits to the surface are sufficient for the beetle to re-establish the constitution of the bubble.<ref>{{cite book |last=Schmidt-Nielsen |first=Knut |title=Animal Physiology: Adaptation and Environment |chapter-url=https://books.google.com/books?id=Af7IwQWJoCMC&pg=PA55|edition=5th |date=January 15, 1997|publisher=[[Cambridge University Press]] |isbn=978-0-521-57098-5 |page=55 |chapter=Insect Respiration}}</ref>

===Circulatory system===
Like other insects, beetles have [[open circulatory system]]s, based on [[hemolymph]] rather than blood. As in other insects, a segmented tube-like heart is attached to the dorsal wall of the [[circulatory system#Nonhuman|hemocoel]]. It has paired inlets or ''ostia'' at intervals down its length, and circulates the hemolymph from the main cavity of the haemocoel and out through the anterior cavity in the head.<ref>{{cite book |last=Miller |first=T. A. |editor1=Kerkut, G. A. |editor2=Gilbert, L. I. |title=Comprehensive Insect Physiology, Biochemistry and Pharmacology. Volume 3: Integument, Respiration and Circulation |publisher=Pergamom Press |date=1985 |pages=289–355 |chapter=Chapter 8: Structure and Physiology of the Circulatory System |isbn=978-0-08-030804-3}}</ref>

===Specialized organs===
Different glands are specialized for different pheromones to attract mates. Pheromones from species of [[Rutelinae]] are produced from [[epithelial cell]]s lining the inner surface of the apical abdominal segments; amino acid-based pheromones of [[Melolonthinae]] are produced from eversible glands on the abdominal apex. Other species produce different types of pheromones. [[Dermestid]]s produce [[ester]]s, and species of [[Elateridae]] produce [[aldehyde|fatty acid-derived aldehyde]]s and [[acetate]]s.<ref name=insenc/> To attract a mate, fireflies ([[Lampyridae]]) use modified fat body cells with transparent surfaces backed with reflective uric acid crystals to produce light by [[bioluminescence]]. Light production is highly efficient, by oxidation of [[Firefly luciferin|luciferin]] catalyzed by enzymes ([[luciferase]]s) in the presence of [[adenosine triphosphate]] (ATP) and oxygen, producing [[oxyluciferin]], carbon dioxide, and light.<ref name=insenc/>

[[Tympanal organ]]s or hearing organs consist of a membrane (tympanum) stretched across a frame backed by an air sac and associated sensory neurons, are found in two families.<ref name="Scoble">{{cite book |author=Scoble, M. J. |title=The Lepidoptera: Form, function, and diversity |url=https://archive.org/details/lepidopteraformf0000scob |url-access=registration |year=1992 |publisher=Oxford University Press |isbn=978-1-4020-6242-1}}</ref> Several species of the genus ''[[Cicindela]]'' (Carabidae) have hearing organs on the dorsal surfaces of their first abdominal segments beneath the wings; two tribes in the [[Dynastinae]] (within the [[Scarabaeidae]]) have hearing organs just beneath their pronotal shields or neck membranes. Both families are sensitive to ultrasonic frequencies, with strong evidence indicating they function to detect the presence of bats by their ultrasonic echolocation.<ref name=insenc/>

==Reproduction and development==
Beetles are members of the [[Order (biology)|superorder]] [[Holometabola]], and accordingly most of them undergo complete [[metamorphosis]]. The typical form of metamorphosis in beetles passes through four main stages: the [[egg]], the [[larva]], the [[pupa]], and the [[imago]] or adult.<ref name="Winkler">{{cite book |last=Winkler|first=Josef Rudolf |title=A Book of Beetles|url=https://books.google.com/books?id=xP5CAAAAYAAJ|year=1964|publisher=[[Spring Books]] Science |isbn=|pages=30–32}}</ref> The larvae are commonly called [[Larva|grubs]] and the pupa sometimes is called the chrysalis. In some species, the pupa may be enclosed in a cocoon constructed by the larva towards the end of its final [[instar]]. Some beetles, such as typical members of the families [[Meloidae]] and [[Rhipiphoridae]], go further, undergoing [[hypermetamorphosis]] in which the first instar takes the form of a [[triungulin]].<ref>{{cite journal |url=https://www.researchgate.net/publication/242221698 |author1=Ozbek, H. |author2=Szalokia, D. |date=1998 |title=A contribution to the knowledge of the Meloidae (Coleoptera) fauna of Turkey along with new record |journal=Turkish Journal of Zoology |volume=22 |pages=23–40}}</ref>

===Mating===
[[File:Punctate Flower Chafer.jpg|thumb|[[Punctate flower chafer]]s (''Neorrhina punctata'', Scarabaeidae) mating]]

Some beetles have intricate mating behaviour. [[Pheromone]] communication is often important in locating a mate.
Different species use different pheromones. [[Scarab beetle]]s such as the [[Rutelinae]] use pheromones derived from [[fatty acid synthesis]] and others use pheromones from organic compounds, while other scarabs such as the [[Melolonthinae]] use [[amino acid]]s and terpenoids. Another way beetles find mates is seen in the [[fireflies]] (Lampyridae) which are [[bioluminescent]], with abdominal light-producing organs. The males and females engage in a complex dialog before mating; each species has a unique combination of flight patterns, duration, composition, and intensity of the light produced.<ref name=insenc/>

Before mating, males and females may stridulate, or vibrate the objects they are on. In the Meloidae, the male climbs onto the dorsum of the female and strokes his antennae on her head, palps, and antennae. In ''[[Eupompha]]'', the male draws his antennae along his longitudinal vertex. They may not mate at all if they do not perform the precopulatory ritual.<ref name=insenc/> This mating behavior may be different amongst dispersed populations of the same species. For example, the mating of a [[Russia]]n population of [[tansy beetle]] (''Chrysolina graminis'') is preceded by an elaborate ritual involving the male tapping the female's eyes, pronotum and antennae with its antennae, which is not evident in the population of this species in the [[United Kingdom]].<ref>{{cite journal |author1=Medvedev, L. N. |author2=Pavlov, S. I. |date=1988 |title=Mating behavior of the Chrysomelidae (Coleoptera) |journal=Entomological Review |volume=67 |pages=100–108}}</ref>

In another example, the [[intromittent organ]] of male [[thistle tortoise beetle]]s is a long, tube-like structure called the [[flagellum]] which is thin and curved. When not in use, the flagellum is stored inside the [[abdomen]] of the male and can extend out to be longer than the male when needed. During mating, this organ bends to the complex shape of the female [[reproductive organ]], which includes a coiled duct that the male must penetrate with the organ. Furthermore, these physical properties of the thistle tortioise beetle have been studied because the ability of a thin, flexible structure to harden without buckling or rupturing is mechanically challenging and may have important implications for the development of microscopic [[catheter]]s in modern medicine.<ref>{{Cite journal |last1=Matsumura |first1=Yoko |last2=Kovalev |first2=Alexander E. |last3=Gorb |first3=Stanislav N. |date=December 2017 |title=Penetration mechanics of a beetle intromittent organ with bending stiffness gradient and a soft tip |journal=Science Advances |volume=3 |issue=12 |article-number=eaao5469 |doi=10.1126/sciadv.aao5469 |issn=2375-2548 |pmc=5738233 |pmid=29279866|bibcode=2017SciA....3O5469M }}</ref>

[[Competition (biology)|Competition]] can play a part in the mating rituals of species such as [[burying beetle]]s (''Nicrophorus''), the insects fighting to determine which can mate. Many male beetles are [[Territory (animal)|territorial]] and fiercely defend their territories from intruding males. In such species, the male often has horns on the head or thorax, making its body length greater than that of a female. Copulation is generally quick, but in some cases lasts for several hours. During copulation, [[Spermatozoon|sperm cell]]s are transferred to the female to [[fertilize]] the egg.<ref name="Gilliott"/>

===Life cycle===
[[File:Life cycle of stag beetle.svg|thumb|300px|The life cycle of the [[stag beetle]] includes three [[instar]]s.]]

====Egg====
Essentially all beetles lay eggs, though some [[myrmecophilous]] [[Aleocharinae]] and some [[Chrysomelinae]] which live in mountains or the subarctic are [[ovoviviparous]], laying eggs which hatch almost immediately.<ref name="Winkler" /> Beetle eggs generally have smooth surfaces and are soft, though the [[Cupedidae]] have hard eggs. Eggs vary widely between species: the eggs tend to be small in species with many instars (larval stages), and in those that lay large numbers of eggs.
A female may lay from several dozen to several thousand eggs during her lifetime, depending on the extent of parental care. This ranges from the simple laying of eggs under a leaf, to the parental care provided by [[scarab beetles]], which house, feed and protect their young. The [[Attelabidae]] roll leaves and lay their eggs inside the roll for protection.<ref name=insenc/><ref name=Crowson>{{cite book |last=Crowson |first=R. A. |title=The Biology of the Coleoptera |url=https://books.google.com/books?id=WMXYBAAAQBAJ&pg=PA360 |year=2013 |publisher=[[Elsevier]] Science |isbn=978-1-4832-1760-4 |pages=358–370}}</ref>

====Larva====
The [[larva]] is usually the principal feeding stage of the beetle [[Biological life cycle|life cycle]]. Larvae tend to feed voraciously once they emerge from their eggs. Some feed externally on plants, such as those of certain leaf beetles, while others feed within their food sources. Examples of internal feeders are most [[Buprestidae]] and longhorn beetles. The larvae of many beetle families are predatory like the adults (ground beetles, ladybirds, rove beetles). The larval period varies between species, but can be as long as several years. The larvae of [[skin beetle]]s undergo a degree of reversed development when starved, and later grow back to the previously attained level of maturity. The cycle can be repeated many times (see [[Biological immortality]]).<ref>{{cite journal |last1=Beck |first1=S. D. |last2=Bharadwaj |first2=R. K. |year=1972 |title=Reversed development and cellular ageing in an insect |journal=[[Science (journal)|Science]] |volume=178 |pages=1210–1211 |bibcode=1972Sci...178.1210B |doi=10.1126/science.178.4066.1210 |pmid=4637808 |issue=4066|s2cid=34101370 }}</ref> Larval morphology is highly varied amongst species, with well-developed and sclerotized heads, distinguishable thoracic and abdominal segments (usually the tenth, though sometimes the eighth or ninth).<ref name="Gilliott"/>

[[File:Hercules beetle (larva).jpg|thumb|left|upright=0.6|[[Scarabaeoidea|Scarabaeiform]] larva of [[Hercules beetle]]]]

Beetle larvae can be differentiated from other insect larvae by their hardened, often darkened heads, the presence of chewing mouthparts, and [[Spiracle (arthropods)|spiracle]]s along the sides of their bodies. Like adult beetles, the larvae are varied in appearance, particularly between beetle families. Beetles with somewhat flattened, highly mobile larvae include the ground beetles and rove beetles; their larvae are described as campodeiform. Some beetle larvae resemble hardened worms with dark head capsules and minute legs. These are elateriform larvae, and are found in the [[click beetle]] (Elateridae) and [[darkling beetle]] (Tenebrionidae) families. Some elateriform larvae of click beetles are known as wireworms. Beetles in the [[Scarabaeoidea]] have short, thick larvae described as scarabaeiform, more commonly known as grubs.<ref>{{cite web |url=https://www.amentsoc.org/insects/glossary/terms/scarabaeiform |title=Definition of 'Scarabaeiform' |publisher=[[Amateur Entomologists' Society]] |access-date=2017-01-27}}</ref>

All beetle larvae go through several [[instar]]s, which are the developmental stages between each [[ecdysis|moult]]. In many species, the larvae simply increase in size with each successive instar as more food is consumed. In some cases, however, more dramatic changes occur. Among certain beetle families or genera, particularly those that exhibit parasitic lifestyles, the first instar (the [[planidium]]) is highly mobile to search out a host, while the following instars are more sedentary and remain on or within their host. This is known as [[hypermetamorphosis]]; it occurs in the [[Meloidae]], [[Micromalthidae]], and [[Ripiphoridae]].<ref>{{cite book |author1=Krinsky, W. L. |editor1=Mullen, G. R. |editor2=Durden, L. A. |date=2009 |title=Medical and Veterinary Entomology |edition=2nd |chapter=8 Beetles (''Coleoptera'') |pages=101–115 |publisher=[[Elsevier]] |isbn=978-0-12-372500-4}}</ref> The blister beetle ''[[Epicauta vittata]]'' (Meloidae), for example, has three distinct larval stages. Its first stage, the [[triungulin]], has longer legs to go in search of the eggs of grasshoppers. After feeding for a week it moults to the second stage, called the caraboid stage, which resembles the larva of a [[Carabidae|carabid beetle]]. In another week it moults and assumes the appearance of a [[Scarabaeidae|scarabaeid larva]]—the scarabaeidoid stage. Its penultimate larval stage is the pseudo-pupa or the coarcate larva, which will overwinter and pupate until the next spring.<ref>{{cite web |url=http://bugguide.net/node/view/149686 |title=Hypermetamorphosis of Striped Blister Beetle – ''Epicauta vittata'' |date=2007 |publisher=BugGuide |access-date=2017-01-27}}</ref>

The larval period can vary widely. A fungus feeding staphylinid ''[[Phanerota fasciata]]'' undergoes three moults in 3.2 days at room temperature while ''Anisotoma'' sp. (Leiodidae) completes its larval stage in the fruiting body of slime mold in 2 days and possibly represents the fastest growing beetles. Dermestid beetles, ''Trogoderma inclusum'' can remain in an extended larval state under unfavourable conditions, even reducing their size between moults. A larva is reported to have survived for 3.5 years in an enclosed container.<ref name=insenc/>

====Pupa and adult====
[[File:Eburia quadrigeminata.jpg|thumb|The ivory-marked beetle, ''[[Eburia quadrigeminata]]'', may live up to 40 years inside the [[hardwood]]s on which the larva feeds.]]

As with all holometabolans, beetle larvae pupate, and from these [[pupa]]e emerge fully formed, sexually mature adult beetles, or [[imago]]s. Pupae never have mandibles (they are [[adecticous]]). In most pupae, the appendages are not attached to the body and are said to be [[exarate]]; in a few beetles (Staphylinidae, Ptiliidae etc.) the appendages are fused with the body (termed as [[Pupa#Position in life cycle|obtect]] pupae).<ref name="Gilliott"/>

Adults have extremely variable lifespans, from weeks to years, depending on the species.<ref name="Gilliott"/><ref name="ausbeetle"/> Some wood-boring beetles can have extremely long life-cycles. It is believed that when furniture or house timbers are infested by beetle larvae, the timber already contained the larvae when it was first sawn up. A [[birch]] bookcase 40 years old released adult ''[[Eburia quadrigeminata]]'' ([[Cerambycidae]]), while ''[[Buprestis aurulenta]]'' and other [[Buprestidae]] have been documented as emerging as much as 51 years after manufacture of wooden items.<ref name="Zeng">{{cite web|last1=Zeng|first1=Yong|title=Longest Life Cycle|url=http://entnemdept.ifas.ufl.edu/walker/ufbir/chapters/chapter_12.shtml|publisher=University of Florida|access-date=17 March 2017|date=1995}}</ref>

==Behaviour==
===Locomotion===
[[File:Photinus pyralis Firefly 2.jpg|thumb|left|''[[Photinus pyralis]]'', firefly, in flight]]

The elytra allow beetles to both fly and move through confined spaces, doing so by folding the delicate wings under the elytra while not flying, and folding their wings out just before takeoff. The unfolding and folding of the wings is operated by muscles attached to the wing base; as long as the tension on the radial and cubital veins remains, the wings remain straight.<ref name="insenc" /> Some beetle species (many [[Cetoniinae]]; some [[Scarabaeinae]], [[Curculionidae]] and [[Buprestidae]]) fly with the elytra closed, with the metathoracic wings extended under the lateral elytra margins.<ref>{{Cite journal |last1=Šípek |first1=Petr |last2=Fabrizi |first2=Silvia |last3=Eberle |first3=Jonas |last4=Ahrens |first4=Dirk |date=2016 |title=A molecular phylogeny of rose chafers (Coleoptera: Scarabaeidae: Cetoniinae) reveals a complex and concerted morphological evolution related to their flight mode |url=https://linkinghub.elsevier.com/retrieve/pii/S1055790316300938 |journal=Molecular Phylogenetics and Evolution |volume=101 |pages=163–175 |doi=10.1016/j.ympev.2016.05.012|pmid=27165937 |bibcode=2016MolPE.101..163S |url-access=subscription }}</ref> The altitude reached by beetles in flight varies. One study investigating the flight altitude of the ladybird species ''[[Coccinella septempunctata]]'' and ''[[Harmonia axyridis]]'' using radar showed that, whilst the majority in flight over a single location were at 150–195&nbsp;m above ground level, some reached altitudes of over 1100&nbsp;m.<ref>{{cite journal |author1=Jeffries, Daniel L. |author2=Chapman, Jason |author3=Roy, Helen E. |author3-link=Helen Roy |author4=Humphries, Stuart |author5=Harrington, Richard |author6=Brown, Peter M. J. |author7=Handley, Lori-J. Lawson |title=Characteristics and Drivers of High-Altitude Ladybird Flight: Insights from Vertical-Looking Entomological Radar |date=2013 |journal=[[PLOS ONE]] |volume=8 |issue=2 |doi=10.1371/journal.pone.0082278 |pmid=24367512 |pmc=3867359 |article-number=e82278|bibcode=2013PLoSO...882278J |doi-access=free }}</ref>

Many rove beetles have greatly reduced elytra, and while they are capable of flight, they most often move on the ground: their soft bodies and strong abdominal muscles make them flexible, easily able to wriggle into small cracks.<ref>{{cite book |pages=[https://archive.org/details/encyclopediaento00capi_189/page/n3281 3218]–3219 |title=Encyclopedia of Entomology |url=https://archive.org/details/encyclopediaento00capi_189 |url-access=limited |first1=John L. |last1= Capinera |publisher=Springer Science & Business Media |year=2008 |edition=2 |isbn=978-1-4020-6242-1}}</ref>

Aquatic beetles use several techniques for retaining air beneath the water's surface. Diving beetles (Dytiscidae) hold air between the abdomen and the elytra when diving. Hydrophilidae have hairs on their under surface that retain a layer of air against their bodies. Adult crawling [[water beetle]]s use both their elytra and their hind [[Arthropod leg|coxa]]e (the basal segment of the back legs) in air retention, while [[whirligig beetle]]s simply carry an air bubble down with them whenever they dive.<ref>{{Cite book |year=2001 |chapter=Haliplidae |pages=138–143 |author1=Arnett, R. H. Jr. |author2=Thomas, M. C. |title=American Beetles, Volume 1 |publisher=CRC Press |isbn=978-0-8493-1925-9}}</ref>

===Communication===
Beetles have a variety of ways to communicate, including the use of [[pheromone]]s. The [[mountain pine beetle]] emits a pheromone to attract other beetles to a tree. The mass of beetles are able to overcome the chemical defenses of the tree. After the tree's defenses have been exhausted, the beetles emit an anti-aggregation pheromone. This species can [[stridulate]] to communicate,<ref name="Beetle love">{{cite web|url=http://www.pc.gc.ca/eng/docs/v-g/dpp-mpb/sec2/dpp-mpb2b.aspx|title=Mountain Pine Beetle – Beetle Love|publisher=Parks Canada|access-date=March 13, 2011}}</ref> but others may use sound to defend themselves when attacked.<ref name="stridulation">{{cite journal|last= Meyer-Rochow| first= V.B.| title= Observations on stridulating Australian beetles (Hydrophilidae, Cerambycidae, Passalidae, Dynastinae) using scanning electron microscopical and electrophysiological techniques| journal=Forma et Functio | date=1971| volume= 4| pages= 326–339}}</ref>

===Parental care===

[[File:Scarabaeus laticollis.jpg|upright|thumb|right|A dung beetle rolling dung]]

Parental care is found in a few families<ref>{{cite journal |last=Brandmayr |first=P. |year=1992 |title=Short review of the presocial evolution in Coleoptera |journal=Ethology Ecology and Evolution |volume=4 |pages=7–16}}</ref> of beetle, perhaps for protection against adverse conditions and predators.<ref name=insenc/> The rove beetle ''[[Bledius spectabilis]]'' lives in [[salt marsh]]es, so the eggs and larvae are endangered by the rising [[tide]]. The maternal beetle patrols the eggs and larvae, burrowing to keep them from flooding and [[asphyxiating]], and protects them from the predatory carabid beetle ''[[Dicheirotrichus gustavii]]'' and from the [[parasitism|parasitoidal]] wasp ''[[Barycnemis blediator]]'', which kills some 15% of the larvae.<ref>{{cite journal |last1=Wyatt |first1=T. D. |last2=Foster |first2=W. A. |year=1989 |title=Parental care in the subsocial intertidal beetle, ''Bledius spectabilis'', in relation to parasitism by the ichneumonid wasp, ''Barycnemis blediator'' |journal=[[Behaviour (journal)|Behaviour]] |volume=110 |issue=1–4 |pages=76–92 |jstor=4534785 |doi=10.1163/156853989X00394}}</ref>

[[Burying beetle]]s are attentive parents, and participate in cooperative care and feeding of their offspring. Both parents work to bury small animal carcass to serve as a food resource for their young and build a brood chamber around it. The parents prepare the carcass and protect it from competitors and from early decomposition. After their eggs hatch, the parents keep the larvae clean of fungus and bacteria and help the larvae feed by regurgitating food for them.<ref>{{Cite journal |last1=Milne |first1=Lorus J. |last2=Milne |first2=Margery J. |date=1944 |title=Notes on the Behavior of Burying Beetles (Nicrophorus spp.) |jstor=25005075 |journal=Journal of the New York Entomological Society|volume=52 |issue=4 |pages=311–327}}</ref> Some [[dung beetle]]s provide parental care, collecting herbivore dung and laying eggs within that food supply, an instance of [[mass provisioning]]. Some species do not leave after this stage, but remain to safeguard their offspring.<ref>{{Cite book |last1=Hanski |first1=Ilkka |last2=Yves |first2=Cambefort|title=Dung Beetle Ecology |publisher=Princeton University Press |year=1991 |pages=626–672 |isbn=978-0-691-08739-9}}</ref>

Most other species of beetles do not provide parental care after the eggs have been laid.<ref>{{Cite web |url=http://animals.sandiegozoo.org/animals/beetle|title=Beetle |website=animals.sandiegozoo.org |access-date=2017-07-18}}</ref>

Subsociality, where females guard their offspring, is well-documented in two families of Chrysomelidae, Cassidinae and Chrysomelinae.<ref>{{cite journal |last1=Chaboo |first1=C.S. |last2=Frieiro-Costa |first2=F.A. |last3=Gómez-Zurita |first3=J. |last4=Westerduijn |first4=R. |year=2014 |title=Subsociality in leaf beetles (Coleoptera: Chrysomelidae: Cassidinae, Chrysomelinae) |doi=10.1080/00222933.2014.909060 |journal=Journal of Natural History |volume=48 |pages=1–44 |s2cid=84683405 }}</ref><ref>{{cite journal |last1=Chaboo |first1=C.S. |year=2002 |title=First report of immatures, genitalia and maternal care in Eugenysa columbiana (Boheman) (Coleoptera: Chrysomelidae: Cassidinae: Eugenysini) |journal=The Coleopterists Bulletin |volume=56 |pages=50–67 |doi=10.1649/0010-065x(2002)056[0050:froiga]2.0.co;2 |s2cid=85885981 |url=http://publication.plazi.org/id/4041FFD8FFB4BB59FF9BFFD1926BC44F }}</ref><ref>{{cite journal |last1=Windsor |first1=D.M. |year=1987 |title=Natural History of a Subsocial Tortoise Beetle, Acromis sparsa Boheman (Chrysomelidae, Cassidinae) in Panama |journal=Psyche: A Journal of Entomology |volume=94 |issue=1–2|pages=127–150 |doi=10.1155/1987/19861 |doi-access=free }}</ref><ref>{{cite journal |last1=Reid |first1=C.A.M. |last2=Beatson |first2=M. |last3=Hasenpusch |first3=J. |year=2009 |title=The morphology and biology of Pterodunga mirabile Daccordi, an unusual subsocial chrysomeline (Coleoptera: Chrysomelidae) |journal=J. Nat. Hist. |volume=43 |issue=7–8 |pages=373–398 |doi=10.1080/00222930802586016 |bibcode=2009JNatH..43..373R |s2cid=84744056 }}</ref><ref>Windsor, D.M., Choe, J.C. 1994. Origins of parental care in chrysomelid beetles. In: Jolivet, P.H., Cox, M.L., Petitipierre, E., editors. Novel aspects of the biology of Chrysomelidae. Series Entomologica 50. Dordrecht: Kluwer Academic Publishers; pp. 111–117.</ref>

===Eusociality===
[[Eusociality]] involves cooperative brood care (including brood care of offspring from other individuals), overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups.<ref>{{cite journal |author1=Crespi, B. J. |author2=Yanega, D. |title=The definition of eusociality |journal=[[Behavioral Ecology]] |date=1995 |volume=6 |issue=1 |pages=109–115 |doi=10.1093/beheco/6.1.109}}</ref> Few organisms outside [[Hymenoptera]] exhibit this behavior; the only beetle to do so is the weevil ''[[Austroplatypus incompertus]]''.<ref name=Kent1992>{{cite journal |author1=Kent, D. S. |author2=Simpson, J. A. |name-list-style=amp | year=1992 | title=Eusociality in the beetle ''Austroplatypus incompertus'' (Coleoptera: Curculionidae) | journal=[[Naturwissenschaften]] |volume=79 |issue=2 |pages=86–87 |doi=10.1007/BF01131810|bibcode = 1992NW.....79...86K|s2cid=35534268 }}</ref> This [[Australia]]n species lives in horizontal networks of tunnels, in the [[heartwood]] of ''[[Eucalyptus]]'' trees. It is one of more than 300 species of wood-boring [[Ambrosia beetle]]s which distribute the spores of ambrosia fungi.<ref name="bee">{{cite magazine |url=https://www.newscientist.com/article/mg13418203.100-science-the-australian-beetle-that-behaves-like-a-bee.html |title=Science: The Australian beetle that behaves like a bee |magazine=New Scientist |date=1992-05-09 |access-date=2010-10-31}}</ref> The fungi grow in the beetles' tunnels, providing food for the beetles and their larvae; female offspring remain in the tunnels and maintain the fungal growth, probably never reproducing.<ref name="bee"/><ref name=Kent1992/> Cooperative brood care is also found in the bess beetles ([[Passalidae]]) where the larvae feed on the semi-digested faeces of the adults.<ref>{{cite journal| title=Social behavior in Passalid beetles (Coleoptera: Passalidae): Cooperative brood care| first1=Jack C.| last1=Schuster| first2=Laura B.| last2=Schuster| journal=Florida Entomologist| volume=68| issue=2| year=1985| pages=266–272| url=http://journals.fcla.edu/flaent/article/viewFile/58011/55690| doi=10.2307/3494359| jstor=3494359| access-date=March 17, 2017| archive-date=March 2, 2016| archive-url=https://web.archive.org/web/20160302014348/http://journals.fcla.edu/flaent/article/viewFile/58011/55690| doi-access=free}}</ref>

===Feeding===
[[File:Orange Blister Beetle (Mylabris pustulata) on Ipomoea carnea W IMG 0593.jpg|thumb|left|''[[Hycleus]]'' sp. ([[Meloidae]]) feeding on the petals of ''[[Ipomoea carnea]]'']]

Beetles are able to exploit a wide diversity of food sources available in their many habitats. Some are [[omnivore]]s, eating both plants and animals. Other beetles are highly specialized in their diet. Many species of leaf beetles, longhorn beetles, and weevils are very host-specific, feeding on only a single species of plant. [[Ground beetle]]s and [[rove beetle]]s ([[Staphylinidae]]), among others, are primarily carnivorous and catch and consume many other [[arthropod]]s and small prey, such as earthworms and snails. While most predatory beetles are generalists, a few species have more specific prey requirements or preferences.<ref>{{cite web|url=http://www.zin.ru/animalia/coleoptera/eng/biol3.htm|title=feeding|author=Lobanov, A.L. |year=2002|work=Beetle Biology And Ecology|publisher=Beetles (Coleoptera) and Coleopterologist|access-date=March 13, 2011}}</ref> In some species, digestive ability relies upon a [[symbiotic]] relationship with [[fungi]] - some beetles have yeasts living their guts, including some yeasts previously undiscovered anywhere else.<ref>{{cite book |last= McCoy|first= Peter |date= 2016|title= Radical Mycology: A Treatise on Seeing & Working with Fungi |url= https://archive.org/stream/radical-mycology-a-treatise-on-seeing-and-working-with-fungi/Radical_Mycology_A_treatise_on_seeing_and_working_with_fungi|publisher= Chthaeus Press|page= 187|isbn=978-0-9863996-0-2}}</ref>

Decaying organic matter is a primary diet for many species. This can range from [[Feces|dung]], which is consumed by [[coprophagous]] species (such as certain [[dung beetle|scarab beetle]]s in the [[Scarabaeidae]]), to dead animals, which are eaten by [[necrophagous]] species (such as the [[carrion beetle]]s, [[Silphidae]]). Some beetles found in dung and carrion are in fact predatory. These include members of the [[Histeridae]] and [[Silphidae]], preying on the larvae of [[coprophagous]] and [[necrophagous]] insects.<ref>{{cite journal |author1=Islam, M. |author2=Hossain, A. |author3=Mostafa, M. G. |author4=Hossain, M. M. |date=2016 |title=Forensically important insects associated with the decomposition of mice carrion in Bangladesh |journal=Jahangirnagar University Journal of Biological Science |volume=5 |issue=1 |pages=11–20 |url=http://banglajol.info/index.php/JUJBS/article/view/29739/19949 |doi=10.3329/jujbs.v5i1.29739|doi-access=free }}</ref> Many beetles feed under bark, some feed on wood while others feed on fungi growing on wood or leaf-litter. Some beetles have special [[mycangia]], structures for the transport of fungal spores.<ref>{{Cite journal |last1=Grebennikov |first1=Vasily V. |last2=Leschen |first2=Richard A. B. |date=2010 |title=External exoskeletal cavities in Coleoptera and their possible mycangial functions |journal=Entomological Science |volume=13 |issue=1 |pages=81–98 |doi=10.1111/j.1479-8298.2009.00351.x|s2cid=84593757 }}</ref>

==Ecology==
<!--[[File:Pegesimallus sp robberfly.jpg|thumb|Beetles such as this [[Chrysomelidae|chrysomelid]] (lower left) are preyed upon by insects such as this [[robber fly]].]]-->

[[File:Long-horn Beetle - Ecyrus dasycerus, Leesylvania State Park, Woodbridge, Virginia.jpg|thumb|upright|A [[camouflage]]d [[longhorn beetle]], ''[[Ecyrus dasycerus]]'']]

===Anti-predator adaptations===

Beetles, both adults and larvae, are the prey of many animal [[predator]]s including [[mammals]] from [[bat]]s to [[rodent]]s, [[birds]], [[lizard]]s, [[amphibians]], [[fishes]], [[dragonflies]], [[robberflies]], [[Reduviidae|reduviid bugs]], [[ant]]s, other beetles, and [[spider]]s.<ref name="Evans27">[[#refEvans|Evans & Bellamy (2000)]], pp. 27–28</ref><ref>{{cite book |author=Cott, H. B. |author-link=Hugh B. Cott |date=1940 |title=Adaptive Coloration in Animals |title-link=Adaptive Coloration in Animals |publisher=Methuen |page=[https://archive.org/details/adaptivecolorati00cott/page/414 414]}}</ref> Beetles use a variety of [[anti-predator adaptation]]s to defend themselves. These include [[camouflage]] and [[mimicry]] against predators that hunt by sight,<ref name="Evans"/> toxicity, and defensive behaviour.<ref name="Evans126"/>

====Camouflage====

{{Further|Camouflage}}

Camouflage is common and widespread among beetle families, especially those that feed on wood or vegetation, such as [[leaf beetle]]s (Chrysomelidae, which are often green) and [[weevil]]s. In some species, sculpturing or various colored scales or hairs cause beetles such as the [[avocado]] weevil ''[[Heilipus apiatus]]'' to resemble bird dung or other inedible objects.<ref name="Evans27"/> Many beetles that live in sandy environments blend in with the coloration of that substrate.<ref name="Evans126">[[#refEvans|Evans & Bellamy (2000)]], p. 126</ref>

====Mimicry and aposematism====

[[File:Clyte bélier - MHNT - Vue dorsale.jpg|thumb|left|''[[Clytus arietis]]'' ([[Cerambycidae]]), a [[Batesian mimic]] of wasps]]
{{further|Mimicry|Aposematism}}

Some [[longhorn beetle]]s (Cerambycidae) are effective [[Batesian mimics]] of [[wasp]]s. Beetles may combine coloration with behavioural mimicry, acting like the wasps they already closely resemble. Many other beetles, including [[ladybirds]], [[blister beetle]]s, and [[Lycidae|lycid beetles]] secrete distasteful or toxic substances to make them unpalatable or poisonous, and are often [[aposematic]], where bright or contrasting [[animal coloration|coloration]] warn off predators; many beetles and other insects mimic these chemically protected species.<ref name="Evans"/>

[[File:Blister beetle (26390828032).jpg|thumb|Blister beetles such as ''[[Hycleus]]'' have brilliant [[aposematic]] coloration, warning of their toxicity.]]
[[File:Bloody -nosed Beetle^ Timarcha tenebricosa - Flickr - gailhampshire.jpg|thumb|The bloody-nosed beetle, ''[[Timarcha tenebricosa]]'', [[antipredator adaptation|defending itself]] by releasing a droplet of noxious red liquid (base of leg, on right)|left|172x172px]]

Chemical defence is important in some species, usually advertised by bright aposematic coloration. Some [[Tenebrionidae]] use their posture for releasing noxious chemicals to warn off predators. Chemical defences may serve purposes other than just protection from vertebrates, such as protection from a wide range of microbes. Some species sequester chemicals from the plants they feed on, incorporating them into their own defences.<ref name="Evans126"/>

Other species have special glands to produce deterrent chemicals. The defensive glands of carabid ground beetles produce a variety of [[hydrocarbon]]s, [[aldehyde]]s, [[phenol]]s, [[quinone]]s, [[ester]]s, and [[acid]]s released from an opening at the end of the abdomen. African carabid beetles (for example, ''[[Anthia]]'') employ the same chemicals as ants: [[formic acid]].<ref name="Evans">[[#refEvans|Evans & Bellamy (2000)]]</ref> [[Bombardier beetle]]s have well-developed pygidial glands that empty from the sides of the intersegment membranes between the seventh and eighth abdominal segments. The gland is made of two containing chambers, one for [[hydroquinone]]s and [[hydrogen peroxide]], the other holding hydrogen peroxide and [[catalase]] enzymes. These chemicals mix and result in an explosive ejection, reaching a temperature of around {{convert|100|C|F}}, with the breakdown of hydroquinone to hydrogen, oxygen, and quinone. The oxygen propels the noxious chemical spray as a jet that can be aimed accurately at predators.<ref name=insenc/>

====Other defences====

Large ground-dwelling beetles such as [[Carabidae]], the [[rhinoceros beetle]] and the longhorn beetles defend themselves using strong [[Mandible (insect)|mandibles]], or heavily sclerotised (armored) spines or horns to deter or fight off predators.<ref name="Evans126"/> Many species of weevil that feed out in the open on leaves of plants react to attack by employing a drop-off reflex. Some combine it with [[thanatosis]], in which they close up their appendages and "play dead".<ref name="insenc199">[[#refMcHugh|McHugh (2009)]], p. 199</ref> The click beetles ([[Elateridae]]) can suddenly catapult themselves out of danger by releasing the energy stored by a click mechanism, which consists of a stout spine on the prosternum and a matching groove in the mesosternum.<ref name="Evans27"/> Some species startle an attacker by producing sounds through [[stridulation]].<ref name="stridulation"/>

===Parasitism===

A few species of beetles are [[Parasitism#Basic concepts|ectoparasitic]] on mammals. One such species, ''[[Platypsyllus castoris]]'', parasitises beavers ([[Beaver|''Castor'']] spp.). This beetle lives as a parasite both as a larva and as an adult, feeding on epidermal tissue and possibly on skin secretions and wound exudates. They are strikingly flattened dorsoventrally, no doubt as an adaptation for slipping between the beavers' hairs. They are wingless and eyeless, as are many other ectoparasites.<ref>{{cite journal |author=Peck, Stewart B. |year=2006 |title=Distribution and biology of the ectoparasitic beaver beetle ''Platypsyllus castoris'' Ritsema in North America (Coleoptera: Leiodidae: Platypsyllinae) |journal=Insecta Mundi |volume=20 |url=http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1107&context=insectamundi |issue=1–2 |pages=85–94}}</ref> Others are kleptoparasites of other invertebrates, such as the [[small hive beetle]] (''Aethina tumida'') that infests [[honey bee]] nests,<ref>{{cite journal |doi=10.1051/apido:2004010 |author1=Neumann, P. |author2=Elzen, P. J. |name-list-style=amp |year=2004 |title=The biology of the small hive beetle (''Aethina tumida'', Coleoptera: Nitidulidae): Gaps in our knowledge of an invasive species |journal=Apidologie |volume=35 |issue=3 |pages=229–247 |doi-access=free }}</ref> while many species are parasitic [[inquiline]]s or [[myrmecophily in Staphylinidae|commensal in the nests of ants]].<ref>{{cite web |url=http://www.cals.ncsu.edu/course/ent425/compendium/coleop~1.html |title=Coleoptera |author=Meyer, John R. |date=March 8, 2005 |publisher=[[North Carolina State University]] |access-date=March 13, 2011 |archive-url=https://wayback.archive-it.org/all/20000524004320/http://www.cals.ncsu.edu/course/ent425/compendium/coleop~1.html |archive-date=May 24, 2000  }}</ref> A few groups of beetles are primary [[parasitoid]]s of other insects, feeding off of, and eventually killing their hosts.<ref>{{Cite book|title=Encyclopedia of Entomology|last1=Weber|first1=Donald C.|last2=Saska|first2=Pavel|last3=Chaboo|first3=Caroline S.|publisher=Springer Netherlands|year=2008|isbn=978-1-4020-6242-1|pages=719–721|chapter=Carabid Beetles (Coleoptera: Carabidae) as Parasitoids|doi=10.1007/978-1-4020-6359-6_492}}</ref>

===Pollination===

[[File:Protaetia cuprea - 2019 Zachi Evenor.jpg|thumb|A Copper Flower-Chafer (''[[Protaetia cuprea]] ignicollis'') on a crown daisy (''[[Glebionis coronaria]]'')]]

Beetle-pollinated flowers are usually large, greenish or off-white in color, and heavily scented. Scents may be spicy, fruity, or similar to decaying organic material. Beetles were most likely the first insects to pollinate flowers.<ref>{{cite journal |last1=Livingston |first1=Stephanie |title=This amber-encased beetle may have been one of the first insects to pollinate flowers |journal=Science |date=November 2019 |doi=10.1126/science.aba1758 |s2cid=213876270 |url=https://www.science.org/content/article/amber-encased-beetle-may-have-been-one-first-insects-pollinate-flowers |access-date=10 January 2021|url-access=subscription }}</ref> Most beetle-pollinated flowers are flattened or dish-shaped, with pollen easily accessible, although they may include [[Pollination trap|traps]] to keep the beetle longer. The plants' ovaries are usually well protected from the biting mouthparts of their pollinators. The beetle families that habitually pollinate flowers are the [[Buprestidae]], [[Cantharidae]], [[Cerambycidae]], [[Cleridae]], [[Dermestidae]], [[Lycidae]], [[Melyridae]], [[Mordellidae]], [[Nitidulidae]] and [[Scarabaeidae]].<ref name="Gullan">{{cite book |last=Gullan |first=P. J. |author2=Cranston, P. S. |title=The Insects: An Outline of Entomology |publisher=Wiley, John & Sons |date=2014 |edition=5 |isbn=978-1-4443-3036-6 |page=314}}</ref> Beetles may be particularly important in some parts of the world such as semiarid areas of southern Africa and [[southern California]]<ref>{{cite journal |author1=Jones, G. D. |author2=Jones, S. D. |name-list-style=amp |year=2001 |title=The uses of pollen and its implication for entomology |journal=Neotropical Entomology |volume=30 |issue=3 |pages=314–349 |doi=10.1590/S1519-566X2001000300001|doi-access=free }}</ref> and the montane grasslands of [[KwaZulu-Natal]] in South Africa.<ref name="Ollerton_a">{{cite journal |author1=Ollerton, J. |author2=Johnson, S. D. |author3=Cranmer, L. |author4=Kellie, S. |name-list-style=amp |year=2003 |title=The pollination ecology of an assemblage of grassland asclepiads in South Africa |journal=[[Annals of Botany]] |volume=92 |pages=807–834 |doi=10.1093/aob/mcg206 |issue=6 |pmid=14612378 |pmc=4243623}}</ref>

===Mutualism===

[[File:Ambrosia beetle life cycle.svg|upright=1.2|thumb|
1: Adult [[ambrosia beetle]] burrows into wood and lays eggs, carrying fungal spores in its [[mycangia]].<br />
2: Larva feeds on fungus, which digests wood, removing toxins, to mutual benefit.<br />
3: Larva pupates.|left]]

[[Mutualism (biology)|Mutualism]] is well known in a few beetles, such as the [[ambrosia beetle]], which partners with fungi to digest the wood of dead trees. The beetles excavate tunnels in dead trees in which they cultivate fungal gardens, their sole source of nutrition. After landing on a suitable tree, an ambrosia beetle excavates a tunnel in which it releases spores of its fungal [[symbiont]]. The fungus penetrates the plant's xylem tissue, digests it, and concentrates the nutrients on and near the surface of the beetle gallery, so the weevils and the fungus both benefit. The beetles cannot eat the wood due to toxins, and uses its relationship with fungi to help overcome the defenses of its host tree in order to provide nutrition for their larvae.<ref name="Malloch">{{cite book |last1=Malloch|first1= D. |last2= Blackwell |first2= M. |year=1993|chapter=Dispersal biology of ophiostomatoid fungi|pages= 195–206 |title=Ceratocystis and Ophiostoma: Taxonomy, Ecology and Pathology |editor1= Wingfield, M. J. |editor2= K. A. Seifert |editor3= J. F. Webber |publisher= APS |place=St. Paul |isbn=978-0-89054-156-2}}</ref> Chemically mediated by a bacterially produced polyunsaturated peroxide,<ref name=Scott2008>{{cite journal |last=Scott |first=J. J. |author2=Oh, D. C. |author3=Yuceer, M. C. |author4=Klepzig, K. D. |author5=Clardy, J. |author6= Currie, C. R. |title=Bacterial protection of beetle-fungus mutualism |journal=[[Science (journal)|Science]] |date=2008 |volume=322 |issue=5898 |page=63 |pmid=18832638 |pmc=2761720 |doi = 10.1126/science.1160423|bibcode=2008Sci...322...63S }}</ref> this mutualistic relationship between the beetle and the fungus is [[coevolve]]d.<ref name="Malloch"/><ref>{{cite book|author=Francke-Grossmann, H. |year=1967 |chapter=Ectosymbiosis in wood inhabiting insects|editor=M. Henry|title=Symbiosis|volume=2|publisher=[[Academic Press]]|location=New York|pages=141–205}}</ref>
[[File:Bug in Tharparkar District.jpg|alt=Beetle found in Tharparkar District|thumb|Tenebrionid beetle in the [[Tharparkar|Thar Desert]]]]

===Tolerance of extreme environments===

[[File:Stenocara gracilipes.jpg|thumb|The fogstand beetle of the [[Namib Desert]], ''[[Stenocara gracilipes]]'', is able to survive by [[fog collection|collecting water from fog]] on its back.]]

{{Further|Insect thermoregulation|Insect winter ecology}}

About 90% of beetle species enter a period of adult [[diapause]], a quiet phase with reduced metabolism to tide unfavourable environmental conditions. Adult diapause is the most common form of diapause in Coleoptera. To endure the period without food (often lasting many months) adults prepare by accumulating reserves of lipids, glycogen, proteins and other substances needed for resistance to future hazardous changes of environmental conditions. This diapause is induced by signals heralding the arrival of the unfavourable season; usually the cue is [[photoperiodic]]. Short (decreasing) day length serves as a signal of approaching winter and induces winter diapause (hibernation).<ref>{{cite journal |last1=Hodek |first1=Ivo |title=Review Article: Adult diapause in Coleoptera |journal=Psyche: A Journal of Entomology |volume=2012 |pages=1–10 |date=2012 |doi=10.1155/2012/249081 |doi-access=free }}</ref> A study of hibernation in the Arctic beetle ''[[Pterostichus brevicornis]]'' showed that the body fat levels of adults were highest in autumn with the [[alimentary canal]] filled with food, but empty by the end of January. This loss of body fat was a gradual process, occurring in combination with dehydration.<ref>{{cite journal |title=Hibernation in the Arctic beetle, ''Pterostichus brevicornis'', in Alaska |author1=Kaufmann, T. |date=1971 |journal=Journal of the Kansas Entomological Society |volume=44 |issue=1 |pages=81–92}}</ref>

All insects are [[poikilotherm]]ic,<ref name='Outline'>{{cite book |author1=Gullan, P. J. |author2=Cranston, P. S. |date=1994 |title=The Insects: An Outline of Entomology |publisher=Chapman and Hall |isbn=978-0-412-49360-7 |pages=103–104}}</ref> so the ability of a few beetles to live in extreme environments depends on their resilience to unusually high or low temperatures. The [[bark beetle]] ''[[Pityogenes chalcographus]]'' can survive {{gaps|−39|°C}} whilst overwintering beneath tree bark;<ref>{{cite journal |author1=Lombadero, Maria J. |author2=Ayres, Matthew P. |author3=Ayres, Bruce D. |author4=Reeve, John D. |title=Cold tolerance of four species of bark beetle (Coleoptera: Scolytidae) in North America |journal=Environmental Ecology |volume=29 |issue=3 |date=2000 |pages=421–432 |url=http://www.dartmouth.edu/~mpayres/pubs/Fina.Cold.pdf |archive-url=https://web.archive.org/web/20070417144045/http://www.dartmouth.edu/~mpayres/pubs/Fina.Cold.pdf |archive-date=2007-04-17 |url-status=live}}</ref> the Alaskan beetle ''[[Cucujus]] clavipes puniceus'' is able to withstand {{gaps|−58|°C}}; its larvae may survive {{gaps|−100|°C}}.<ref>{{cite journal |author1=Sformo, T. |author2=Walters, K. |author3=Jeannet, K. |author4=Wowk, B. |author5=Fahy, G. M. |author6=Barnes, B. M. |author7=Duman, J. G. |title=Deep supercooling, vitrification and limited survival to −100°C in the Alaskan beetle ''Cucujus clavipes puniceus'' (Coleoptera: Cucujidae) larvae |journal=[[Journal of Experimental Biology]] |date=2010 |volume=213 |issue=3 |pages=502–509 |doi=10.1242/jeb.035758 |pmid=20086136|doi-access=free |bibcode=2010JExpB.213..502S }}</ref> At these low temperatures, the formation of ice crystals in internal fluids is the biggest threat to survival to beetles, but this is prevented through the production of antifreeze proteins that stop water molecules from grouping together. The low temperatures experienced by ''Cucujus clavipes'' can be survived through their deliberate dehydration in conjunction with the antifreeze proteins. This concentrates the antifreezes several fold.<ref>{{cite news |url=https://www.bbc.co.uk/nature/21923937 |archive-url=https://web.archive.org/web/20130326183841/http://www.bbc.co.uk/nature/21923937 |archive-date=March 26, 2013 |title=The life of extremophiles: Surviving in hostile habitats |last1=Brooks |first1=Christopher |date=2013-03-26 |publisher=BBC Nature |access-date=2017-03-16}}</ref> The [[hemolymph]] of the mealworm beetle ''[[Tenebrio molitor]]'' contains several [[antifreeze protein]]s.<ref>{{cite journal |author1=Graham, L. A |author2=Liou, Y. C. |author3=Walker, V. K. |author4=Davies, P. L. |title=Hyperactive antifreeze protein from beetles |journal=[[Nature (journal)|Nature]] |volume=388 |issue=6644 |pages=727–728 |date=August 1997 |doi=10.1038/41908 |quote=The yellow mealworm beetle, ''Tenebrio molitor'', contains a family of small Cys-rich and Thr-rich thermal hysteresis proteins that depress the hemolymph freezing point below the melting point by as much as 5.58°C(ΔT=thermal hysteresis). Thermal hysteresis protein expression was evaluated throughout development and after exposure to altered environmental conditions. |pmid=9285581 |bibcode=1997Natur.388..727G|s2cid=205029622 |doi-access=free }}</ref> The Alaskan beetle ''[[Upis ceramboides]]'' can survive −60&nbsp;°C: its [[cryoprotectant]]s are [[xylomannan]], a molecule consisting of a [[sugar]] bound to a [[fatty acid]],<ref>{{cite journal |author1=Walters, K. R. Jr |author2=Serianni, A. S. |author3=Sformo, T. |author4=Barnes, B. M. |author5=Duman, J. G. |title=A nonprotein thermal hysteresis-producing xylomannan antifreeze in the freeze-tolerant Alaskan beetle Upis ceramboides |journal=[[PNAS]] |volume=106 |issue=48| year=2009 |pages= 20210–20215 |doi=10.1073/pnas.0909872106 |pmid=19934038 |pmc=2787118|bibcode=2009PNAS..10620210W |doi-access=free }}</ref> and the sugar-alcohol, [[threitol]].<ref>{{cite journal| title=Cryoprotectant biosynthesis and the selective accumulation of threitol in the freeze-tolerant Alaskan beetle, ''Upis ceramboides'' |author1=Walters, K. R. Jr.|author2=Pan, Q. |author3=Serianni, A. S. |author4=Duman, J. G. | journal=[[Journal of Biological Chemistry]] |year=2009 |volume= 284 |issue=25 | pages=16822–16831 | doi=10.1074/jbc.M109.013870 | pmid=19403530 | pmc=2719318|doi-access=free }}</ref>

Conversely, desert dwelling beetles are adapted to tolerate high temperatures. For example, the [[Tenebrionid]] beetle ''[[Onymacris rugatipennis]]'' can withstand {{gaps|50|°C}}.<ref>{{cite journal |author=Edney, E. B. |date=1971 |title=The body temperature of tenebrionid beetles in the Namib desert of southern Africa |journal=[[Journal of Experimental Biology]] |volume=55 |issue=1 |pages=253–272 |doi=10.1242/jeb.55.1.253 |bibcode=1971JExpB..55..253E |url=http://jeb.biologists.org/content/jexbio/55/1/253.full.pdf |archive-url=https://web.archive.org/web/20170211080953/http://jeb.biologists.org/content/jexbio/55/1/253.full.pdf |archive-date=2017-02-11 |url-status=live}}</ref> Tiger beetles in hot, sandy areas are often whitish (for example, ''[[Habroscelimorpha dorsalis]]''), to reflect more heat than a darker color would. These beetles also exhibits behavioural adaptions to tolerate the heat: they are able to stand erect on their tarsi to hold their bodies away from the hot ground, seek shade, and turn to face the sun so that only the front parts of their heads are directly exposed.<ref>{{cite journal|doi=10.1093/aesa/83.5.911 |title=Seasonal activity and thermoregulatory behavior of ''Cicindela patruela'' (Coleoptera: Cicindelidae) |journal=Annals of the Entomological Society of America |volume=83 |issue=5 |pages=911–915 |year=1990 |last1=Knisley |first1=C. B. |last2=Schultz |first2=T. D. |last3=Hasewinkel |first3=T. H. }}</ref>

The fogstand beetle of the [[Namib Desert]], ''[[Stenocara gracilipes]]'', is able to [[fog collection|collect water from fog]], as its elytra have a textured surface combining [[hydrophilic]] (water-loving) bumps and waxy, [[hydrophobic]] troughs. The beetle faces the early morning breeze, holding up its abdomen; droplets condense on the elytra and run along ridges towards their mouthparts. Similar adaptations are found in several other Namib desert beetles such as ''[[Onymacris unguicularis]]''.<ref>{{Cite journal| doi = 10.1038/35102108| volume = 414| issue = 6859| pages = 33–34| last1 = Parker| first1 = Andrew R.| last2 = Lawrence| first2 = Chris R.| title = Water capture by a desert beetle| journal = Nature| date = 2001-11-01| pmid=11689930| bibcode = 2001Natur.414...33P| s2cid = 34785113}}</ref>

Some terrestrial beetles that exploit shoreline and floodplain habitats have physiological adaptations for surviving floods. In the event of flooding, adult beetles may be mobile enough to move away from flooding, but larvae and pupa often cannot. Adults of ''[[Cicindela togata]]'' are unable to survive immersion in water, but larvae are able to survive a prolonged period, up to 6 days, of [[Hypoxia (environmental)|anoxia]] during floods. Anoxia tolerance in the larvae may have been sustained by switching to anaerobic metabolic pathways or by reducing metabolic rate.<ref>{{cite journal |author1=Hoback, W. Wyatt |author2=Stanley, David W. |author3=Higley, Leon G. |author4=Barnhart, M. Christopher |title=Survival of immersion and anoxia by larval tiger beetles, ''Cicindela togata'' |journal=The American Midland Naturalist |volume=140 |issue=1 |pages=27–33 |doi=10.1674/0003-0031(1998)140[0027:SOIAAB]2.0.CO;2|year=1998 |s2cid=86163282 }}</ref> Anoxia tolerance in the adult carabid beetle ''[[Pelophilia borealis]]'' was tested in laboratory conditions and it was found that they could survive a continuous period of up to 127 days in an atmosphere of 99.9% nitrogen at 0&nbsp;°C.<ref>{{cite journal |title=Anaerobiosis in the overwintering beetle ''Pelophila borealis'' |author1=Conradi-Larsen, Else-Margrete |author2=Sømme, Lauritz |date=1973 |journal=Nature |volume=245 |issue=5425 |pages=388–390 |doi=10.1038/245388a0|bibcode=1973Natur.245..388C |s2cid=4288059 }}</ref>

===Migration===

{{Main|Insect migration}}

Many beetle species undertake annual mass movements which are termed as migrations. These include the pollen beetle ''[[Meligethes aeneus]]''<ref>{{cite web |url=http://www.fwi.co.uk/arable/half-of-the-uk-sees-start-of-pollen-beetle-migration.htm |title=Half of the UK sees start of pollen beetle migration |author1=Allison, R. |date=2015-03-17 |access-date=2017-03-16}}</ref> and many species of [[Coccinellidae|coccinellids]].<ref>{{cite journal |doi=10.1111/j.1469-185X.1962.tb01609.x |title=Migration of Terrestrial Arthropods in Relation to Habitat |journal=Biological Reviews |volume=37 |issue=2 |pages=171–211 |year=1962 |last1=Southwood |first1=T. R. E.|s2cid=84711127 }}</ref> These mass movements may also be opportunistic, in search of food, rather than seasonal. A 2008 study of an unusually large outbreak of Mountain Pine Beetle (''[[Dendroctonus ponderosae]]'') in [[British Columbia]] found that beetles were capable of flying 30–110&nbsp;km per day in densities of up to 18,600 beetles per hectare.<ref>{{cite book |title=Migration: The Biology of Life on the Move |author1=Dingle, H. |date=2014 |publisher=Oxford University Press}}</ref>

==Relationship to humans==
===In ancient cultures===
<!--[[File:Egyptian Dung beetle2008.jpg|thumb|A large [[Scarab (artifact)|scarab]] statue in [[Karnak]]]]-->
{{main|Scarab (artifact)}}
{{hiero|name=Scarabee|pron=ḫpr|image=<hiero>xpr</hiero>|align=left|era=egypt|gardiner=L1}}
[[File:Egypt.KV6.04.jpg|thumb|A scarab in the [[Valley of the Kings]]]]

Several species of dung beetle, especially the sacred scarab, ''[[Scarabaeus sacer]]'', were revered in [[Ancient Egypt]].<ref name="egyptian">{{cite book |title=Beetles |publisher=Michelle Bison |author=Zabludoff, Marc |year=2008 |location=Malaysia |pages=14–17 |isbn=978-0-7614-2532-8}}</ref><ref>{{cite web |author=Cambefort, Yves |url=http://www.insects.org/ced1/beetles_rel_sym.html |title=Beetles as religious symbols |publisher=Insects.org |date=2011 |access-date=February 10, 2017 |archive-url=https://web.archive.org/web/20161018110844/http://www.insects.org/ced1/beetles_rel_sym.html |archive-date=October 18, 2016  }}</ref> The hieroglyphic image of the beetle may have had existential, fictional, or ontologic significance.<ref>{{cite web |url=http://www.reshafim.org.il/ad/egypt/bestiary/insects.htm |title=Ancient Egyptian bestiary: Insects |date=January 2002 |access-date=July 19, 2011 |author=Dollinger, André |archive-url=https://web.archive.org/web/20150401025144/http://www.reshafim.org.il/ad/egypt/bestiary/insects.htm |archive-date=April 1, 2015  }}</ref> Images of the scarab in bone, [[ivory]], stone, [[Egyptian faience]], and precious metals are known from the Sixth Dynasty and up to the period of Roman rule. The scarab was of prime significance in the funerary cult of ancient Egypt.<ref>{{cite web |url=http://www.all-about-egypt.com/egyptian-symbols.html |title=Egyptian Symbols |publisher=All-About-Egypt |year=2006 |access-date=July 19, 2011 |author=Morales-Correa, Ben |archive-url=https://web.archive.org/web/20110820175032/http://www.all-about-egypt.com/egyptian-symbols.html |archive-date=August 20, 2011  }}</ref> The scarab was linked to [[Khepri]], the god of the rising [[sun]], from the supposed resemblance of the rolling of the dung ball by the beetle to the rolling of the sun by the god.<ref name="egyptian"/> Some of ancient Egypt's neighbors adopted the scarab motif for [[scaraboid seal|seals]] of varying types. The best-known of these are the Judean [[LMLK seal]]s, where eight of 21 designs contained scarab beetles, which were used exclusively to stamp impressions on storage jars during the reign of [[Hezekiah]].<ref>{{cite book |last1=Ussishkin |first1=David |title=The New Archaeological Excavations at Lachish (1973–1994) |date=2004 |publisher=Institute of Archaeology of [[Tel Aviv University]] |location=Tel Aviv |url=http://archaeology.tau.ac.il/?page_id=2059 |access-date=December 28, 2015 |archive-url=https://web.archive.org/web/20180703050411/http://archaeology.tau.ac.il/?page_id=2059 |archive-date=July 3, 2018  }}</ref> Beetles are mentioned as a symbol of the sun, as in ancient Egypt, in [[Plutarch]]'s 1st century ''[[Moralia]]''.<ref>[https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Plutarch/Moralia/Isis_and_Osiris*/E.html#ref373 "Isis and Osiris"], ''Moralia'', in volume V of the [[Loeb Classical Library]], 1936. "The race of beetles has no female, but all the males eject their sperm into a round pellet of material which they roll up by pushing it from the opposite side, just as the sun seems to turn the heavens in the direction opposite to its own course, which is from west to east.</ref> The [[Greek Magical Papyri]] of the 2nd century BC to the 5th century AD describe scarabs as an ingredient in a spell.<ref>{{cite book |editor=Betz, H. D. |editor-link=Hans Dieter Betz |date=1992 |title=The Greek Magical Papyri in Translation (Including the Demotic Spells) |edition=2nd |publisher=[[University of Chicago Press]] |pages=IV.52–85; VII.520; XII.101; XIII.1065–1070; XXXVI.170}}</ref>

[[Pliny the Elder]] discusses beetles in his ''[[Natural History (Pliny)|Natural History]]'',<ref name='PlinyXI'>{{cite web |url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.02.0137%3Abook%3D11%3Achapter%3D1 |title=''Natural History'' Book 11 |author=Pliny the Elder |publisher=Perseus.tufts.edu |access-date=January 25, 2017 |author-link=Pliny the Elder }}</ref> describing the [[Lucanus cervus|stag beetle]]: "Some insects, for the preservation of their wings, are covered with {{As written|an erust}} ([[elytra]])—the beetle, for instance, the wing of which is peculiarly fine and frail. To these insects a sting has been denied by Nature; but in one large kind we find horns of a remarkable length, two-pronged at the extremities, and forming pincers, which the animal closes when it is its intention to bite."<ref name='PlinyXI Book34'>{{cite web |url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.02.0137%3Abook%3D11%3Achapter%3D34 |title=''Natural History'' Book 11, Chapter 34 |author=Pliny the Elder |publisher=Perseus.tufts.edu |access-date=2017-01-25|author-link=Pliny the Elder }}</ref><ref name='Beavis'>{{cite book |author=Beavis, I. C. |date=1988 |title=Insects and other Invertebrates in Classical Antiquity |publisher=[[University of Exeter]] |pages=153–154}}</ref> The stag beetle is recorded in a Greek myth by [[Nicander]] and recalled by [[Antoninus Liberalis]] in which [[Cerambus]]{{efn|The wood-gnawing longhorn beetle genus ''[[Cerambyx]]'' is named for him.}} is turned into a beetle: "He can be seen on trunks and has hook-teeth, ever moving his jaws together. He is black, long and has hard wings like a great dung beetle".<ref>[[Antoninus Liberalis]]. Metamorphoses. Trans. Celoria, F. 1992. ''The Metamorphoses of Antoninus Liberalis: A translation with a commentary''. London and New York, Routledge.</ref> The story concludes with the comment that the beetles were used as toys by young boys, and that the head was removed and worn as a pendant.<ref name='Beavis'/><ref>{{cite journal |last=Sprecher-Uebersax |first=E. |date=2008 |title=The Stag Beetle Lucanus Cervus (Coleoptera, Lucanidae) in Art and Mythology |journal=Revue d'Écologie |volume=63 |pages=145–151}}</ref>

===As pests===
[[File:Cotton boll weevil.jpg|thumb|left|[[Cotton boll weevil]]]]

About 75% of beetle species are phytophagous in both the larval and adult stages. Many feed on economically important plants and stored plant products, including trees, cereals, tobacco, and dried fruits.<ref name="Gilliott"/> Some, such as the [[boll weevil]], which feeds on cotton buds and flowers, can cause extremely serious damage to agriculture. The boll weevil crossed the [[Rio Grande]] near [[Brownsville, Texas|Brownsville]], [[Texas]], to enter the [[United States]] from [[Mexico]] around 1892,<ref name="msstate"/> and had reached southeastern [[Alabama]] by 1915. By the mid-1920s, it had entered all cotton-growing regions in the US, traveling {{convert|40|to(-)|160|mi|-1}} per year. It remains the most destructive cotton pest in North America. [[Mississippi State University]] has estimated, since the boll weevil entered the United States, it has cost cotton producers about $13&nbsp;billion, and in recent times about $300&nbsp;million per year.<ref name="msstate">{{cite web |url=http://www.bollweevil.ext.msstate.edu/webpage_history.htm |work=Economic impacts of the boll weevil |title=History of the Boll Weevil in the United States |author=Mississippi State University |archive-url=https://web.archive.org/web/20080512023346/http://www.bollweevil.ext.msstate.edu/webpage_history.htm |archive-date=May 12, 2008}}</ref>

The [[bark beetle]], [[elm leaf beetle]] and the Asian longhorned beetle (''[[Anoplophora glabripennis]]'')<ref>{{cite journal |doi=10.1080/07060660309506983 |title=Nonindigenous species introductions: A threat to Canada's forests and forest economy |journal=Canadian Journal of Plant Pathology |volume=24 |issue=2 |pages=103–110 |year=2002 |last1=Allen |first1=E. A. |last2=Humble |first2=L. M.|bibcode=2002CaJPP..24..103A |s2cid=85073955 }}</ref> are among the species that attack [[elm]] trees. Bark beetles ([[Scolytidae]]) carry [[Dutch elm disease]] as they move from infected breeding sites to healthy trees. The disease has devastated elm trees across Europe and North America.<ref>{{cite book |doi=10.1007/978-1-4615-4507-1_3 |chapter=Insect Vector Behavior and the Evolution of Dutch Elm Disease |title=The Elms |page=47 |year=2000 |last1=Webber |first1=Joan F. |isbn=978-1-4613-7032-1}}</ref>

[[File:Potato beetle larvae.jpg|thumb|Larvae of the [[Colorado potato beetle]], ''Leptinotarsa decemlineata'', a serious crop pest]]

Some species of beetle have evolved immunity to insecticides. For example, the [[Colorado potato beetle]], ''Leptinotarsa decemlineata'', is a destructive pest of potato plants. Its hosts include other members of the [[Solanaceae]], such as [[nightshade]], [[tomato]], [[eggplant]] and [[capsicum]], as well as the potato. Different populations have between them developed resistance to all major classes of insecticide.<ref>{{cite journal |author1=Alyokhin, A. |author2=Baker, M. |author3=Mota-Sanchez, D. |author4=Dively, G. |author5=Grafius, E. |year=2008 |title=Colorado potato beetle resistance to insecticides |journal=American Journal of Potato Research |volume=85 |pages=395–413 |doi=10.1007/s12230-008-9052-0 |issue=6|s2cid=41206911 }}</ref> The Colorado potato beetle was evaluated as a tool of [[entomological warfare]] during [[World War II]], the idea being to use the beetle and its larvae to damage the crops of enemy nations.<ref name=lockwoodbost>{{cite news |author1=Lockwood, Jeffrey A. |url=http://www.boston.com/news/globe/ideas/articles/2007/10/21/bug_bomb |title=Bug bomb:Why our next terrorist attack could come on six legs |newspaper=Boston Globe |date=2007-10-21 |access-date=2017-02-13}}</ref> Germany tested its Colorado potato beetle weaponisation program south of [[Frankfurt]], releasing 54,000 beetles.<ref name=heather>{{cite book |author1=Heather, Neil W. |author2=Hallman, Guy J. |title=Pest Management and Phytosanitary Trade Barriers |url=https://archive.org/details/pestmanagementph00hall |url-access=limited |publisher=CABI |date=2008 |pages=[https://archive.org/details/pestmanagementph00hall/page/n27 17]–18 |isbn=978-1-84593-343-2 |doi=10.1079/9781845933432.0000}}</ref>

The [[death watch beetle]], ''Xestobium rufovillosum'' ([[Ptinidae]]), is a serious pest of older wooden buildings in Europe. It attacks [[hardwood]]s such as [[oak]] and [[chestnut]], always where some fungal decay has taken or is taking place. The actual introduction of the pest into buildings is thought to take place at the time of construction.<ref>{{cite web |url=http://www.bodley.ox.ac.uk/dept/preservation/training/pests/watch.htm |title=Pests – Death watch beetle |publisher=[[University of Oxford]] |work=Conservation and collective care |year=2005 |access-date=July 17, 2011 |author=Adcock, Edward |archive-url=https://web.archive.org/web/20110710144935/http://www.bodley.ox.ac.uk/dept/preservation/training/pests/watch.htm |archive-date=July 10, 2011  }}</ref>

Other pests include the coconut hispine beetle, ''[[Brontispa longissima]]'', which feeds on young [[leaves]], [[seedlings]] and mature [[coconut]] trees, causing serious economic damage in the [[Philippines]].<ref>{{cite journal |doi=10.1111/ens.12048 |title=Suitability of four palm species for the development of the invasive pest ''Brontispa'' longissima(Coleoptera: Chrysomelidae) in the field |journal=Entomological Science |volume=17 |issue=2 |pages=265–268 |year=2014 |last1=Takano |first1=Shun-Ichiro |last2=Takasu |first2=Keiji |last3=Fushimi |first3=Tsutomu |last4=Ichiki |first4=Ryoko T. |last5=Nakamura |first5=Satoshi|s2cid=85910791 }}</ref> The [[mountain pine beetle]] is a destructive pest of mature or weakened [[lodgepole pine]], sometimes affecting large areas of Canada.<ref>{{cite web |url=http://mpb.cfs.nrcan.gc.ca/biology/introduction_e.html |title=The Mountain Pine Beetle in British Columbia |publisher=[[Natural Resources Canada]] |date=August 19, 2008 |access-date=June 24, 2010 |archive-url=https://web.archive.org/web/20100419214859/http://mpb.cfs.nrcan.gc.ca/biology/introduction_e.html |archive-date=April 19, 2010}}</ref>

===As beneficial resources===
[[File:Lady-beetle-close-up.jpg|thumb|left|''[[Coccinella septempunctata]]'', a predatory beetle beneficial to agriculture]]

Beetles can be beneficial to human economics by controlling the populations of pests. The larvae and adults of some species of [[lady beetle]]s ([[Coccinellidae]]) feed on [[aphid]]s that are pests. Other lady beetles feed on [[scale insect]]s, [[whitefly]] and [[mealybug]]s.<ref>{{cite web |url=http://entnemdept.ufl.edu/creatures/beneficial/lady_beetles.htm |title=Insecta: Coleoptera: Coccinellidae |publisher=Institute of Food and Agricultural Services, [[University of Florida]] |date=2014 |access-date=2017-02-12}}</ref> If normal food sources are scarce, they may feed on small [[caterpillar]]s, young [[plant bug]]s, or [[honeydew (secretion)|honeydew]] and [[nectar]].<ref name="BBC news">{{cite news|url=https://news.bbc.co.uk/2/hi/uk_news/england/essex/3715120.stm|title='Deadly ladybird' sighted in UK |date=October 5, 2004 |work=BBC News|access-date=June 17, 2010}}</ref> [[Ground beetle]]s (Carabidae) are common [[predator]]s of many insect pests, including fly eggs, caterpillars, and wireworms.<ref>{{cite journal |author=Kromp, B. |year=1999 |title=Carabid beetles in sustainable agriculture: a review on pest control efficacy, cultivation aspects and enhancement |journal=[[Agriculture, Ecosystems and Environment]] |volume=74 |issue=1–3 |pages=187–228 |doi=10.1016/S0167-8809(99)00037-7|bibcode=1999AgEE...74..187K }}</ref> Ground beetles can help to control [[weed]]s by eating their seeds in the soil, reducing the need for [[herbicide]]s to protect crops.<ref>{{Cite web| title = Beetles play an important role in reducing weeds| publisher = Rothamsted Research| access-date = March 14, 2017| url = http://www.rothamsted.ac.uk/news/beetles-play-important-role-reducing-weeds| archive-date = July 3, 2018| archive-url = https://web.archive.org/web/20180703050543/https://www.rothamsted.ac.uk/news/beetles-play-important-role-reducing-weeds}}</ref> The effectiveness of some species in reducing certain plant populations has resulted in the deliberate introduction of beetles in order to control weeds. For example, the genus ''[[Calligrapha]]'' is native to North America but has been used to control ''[[Parthenium hysterophorus]]'' in India and ''[[Ambrosia artemisiifolia]]'' in Russia.<ref name='ISC'>{{cite web |url=http://www.cabi.org/isc/datasheet/57506 |title=''Zygogramma bicolorata'' (Mexican beetle) |date=2012 |publisher=Invasive Species Compendium |access-date=2017-02-12}}</ref><ref>{{cite journal |author1=Kovalev, O. V. |author2=Reznik, S. Y. |author3=Cherkashin, V. N. |date=1983 |title=Specific features of the methods of using ''Zygogramma'' Chevr. (Coleoptera, Chrysomelidae) in biological control of ragweeds (''Ambrosia artemisiifolia'' L., ''A. psilostachya'' D.C.) |journal=Entomologicheskoe Obozrenije |language=ru |volume=62 |pages=402–408}}</ref>

[[Dung beetles]] (Scarabidae) have been successfully used to reduce the populations of pestilent flies, such as ''[[Musca vetustissima]]'' and ''[[Haematobia exigua]]'' which are serious pests of cattle in [[Australia]].<ref name='Bornemissza'>{{cite journal |author=Bornemissza, George |author-link=George Bornemissza |date=1970 |title=Insectary Studies on the Control of Dung Breeding Flies by the Activity of the Dung Beetle, ''Onthophagus Gazella'' F. (Coleoptera: Scarabaeinae) |journal=[[Australian Journal of Entomology]] |volume=9 |pages=31–41|doi=10.1111/j.1440-6055.1970.tb00767.x |doi-access=free }}</ref> The beetles make the dung unavailable to breeding pests by quickly rolling and burying it in the soil, with the added effect of improving soil fertility, tilth, and nutrient cycling.<ref>{{cite journal |author1=Brown, Jacqueline |author2=Scholtz, Clarke H. |author3=Janeau, Jean-Louis |author4=Grellier, Seraphine |author5=Podwojewski, Pascal |name-list-style=amp |year=2010 |title=Dung beetles (Coleoptera: Scarabaeidae) can improve soil hydrological properties |journal=Applied Soil Ecology |volume=46 |issue=1 |pages=9–16 |doi=10.1016/j.apsoil.2010.05.010|bibcode=2010AppSE..46....9B |hdl=2263/14419 |hdl-access=free }}</ref> The [[Australian Dung Beetle Project]] (1965–1985), introduced species of dung beetle to Australia from South Africa and Europe to reduce populations of ''Musca vetustissima'', following successful trials of this technique in [[Hawaii]].<ref name='Bornemissza'/> The [[American Institute of Biological Sciences]] reports that dung beetles, such as ''[[Euoniticellus intermedius]]'', save the United States cattle industry an estimated US$380&nbsp;million annually through burying above-ground livestock feces.<ref>{{cite journal |author1=Losey, John E. |author2=Vaughan, Mace |year=2006 |url=http://www.xerces.org/wp-content/uploads/2008/09/economic_value_insects.pdf |title=The economic value of ecological services provided by insects |journal=BioScience |volume=56 |issue=4 |pages=311–323 |doi=10.1641/0006-3568(2006)56[311:TEVOES]2.0.CO;2 |s2cid=2970747 |access-date=July 17, 2011 |archive-url=https://web.archive.org/web/20180619202116/http://www.xerces.org/wp-content/uploads/2008/09/economic_value_insects.pdf |archive-date=June 19, 2018  }}</ref>

The [[Dermestidae]] are often used in [[taxidermy]] and in the preparation of scientific specimens, to clean soft tissue from bones.<ref>{{cite book |editor=Huffman, Jane E. |editor2=Wallace, John R. |year=2012 |title=Wildlife Forensics: Methods and Applications |volume=6 |series=Developments in Forensic Science |edition=2nd |publisher=[[John Wiley & Sons]] |isbn=978-1-119-95429-3 |chapter=Forensic entomology and wildlife |author1=Tomberlin, Jeffery K. |author2=Sanford, Michelle R. |pages=81–107 |chapter-url=https://books.google.com/books?id=EstjD_GgFvQC&pg=PT123}}</ref> Larvae feed on and remove cartilage along with other soft tissue.<ref>{{cite AV media |url=https://www.youtube.com/watch?v=VxYrVEJp3kY | archive-url=https://ghostarchive.org/varchive/youtube/20211116/VxYrVEJp3kY| archive-date=2021-11-16 | url-status=live|title=Dermestid Beetles working on a female Black Bear skull |year=2014 |access-date=2017-01-26}}{{cbignore}}</ref><ref>{{cite journal |doi=10.1016/j.geobios.2006.06.006 |title=Experimental taphonomy in museums: Preparation protocols for skeletons and fossil vertebrates under the scanning electron microscopy |journal=Geobios |volume=41 |pages=157–181 |year=2008 |last1=Fernández-Jalvo|first1=Yolanda |last2=Monfort |first2=Maria Dolores Marín|issue=1 |bibcode=2008Geobi..41..157F }}</ref>

===As food and medicine===
{{See also|Entomophagy|Insects as food}}
[[File:Mealworm 01 Pengo.jpg|thumb|Mealworms in a bowl for [[Entomophagy|human consumption]]]]

Beetles are the most widely eaten insects, with about 344 species used as food, usually at the larval stage.<ref>{{cite book|title=Creepy crawly cuisine: the gourmet guide to edible insects |last=Ramos-Elorduy |first=Julieta|author2=Menzel, Peter |year=1998 |publisher=Inner Traditions / Bear & Company |isbn=978-0-89281-747-4 |page=5 |url=https://books.google.com/books?id=Q7f1LkFz11gC}}</ref> The [[mealworm]] (the larva of the [[darkling beetle]]) and the [[rhinoceros beetle]] are among the species commonly eaten.<ref>{{cite magazine |last1=Holland |first1=Jennifer S. |title=U.N. Urges Eating Insects; 8 Popular Bugs to Try |url=http://news.nationalgeographic.com/news/2013/13/130514-edible-insects-entomophagy-science-food-bugs-beetles/ |archive-url=https://web.archive.org/web/20130606223425/http://news.nationalgeographic.com/news/2013/13/130514-edible-insects-entomophagy-science-food-bugs-beetles |archive-date=June 6, 2013 |magazine=National Geographic |access-date=January 26, 2017 |date=May 14, 2013}}</ref> A wide range of species is also used in [[folk medicine]] to treat those suffering from a variety of disorders and illnesses, though this is done without clinical studies supporting the efficacy of such treatments.<ref name=Meyer-Rochow>{{cite journal |last=Meyer-Rochow | first=V. B. |title=Therapeutic arthropods and other, largely terrestrial, folk-medicinally important invertebrates: a comparative survey and review. |journal=Journal of Ethnobiology and Ethnomedicine| date=January 2017| volume=13 |issue=9 |article-number=9| doi=10.1186/s13002-017-0136-0| pmid=28173820 | pmc=5296966 | doi-access=free }}</ref>

===As biodiversity indicators===

Due to their habitat specificity, many species of beetles have been suggested as suitable as indicators, their presence, numbers, or absence providing a measure of habitat quality. Predatory beetles such as the tiger beetles ([[Cicindelidae]]) have found scientific use as an indicator taxon for measuring regional patterns of biodiversity. They are suitable for this as their taxonomy is stable; their life history is well described; they are large and simple to observe when visiting a site; they occur around the world in many habitats, with species specialised to particular habitats; and their occurrence by species accurately indicates other species, both vertebrate and invertebrate.<ref>{{cite journal |last1=Pearson |first1=David L. |last2=Cassola |first2=Fabio |title=World-Wide Species Richness Patterns of Tiger Beetles (Coleoptera: Cicindelidae): Indicator Taxon for Biodiversity and Conservation Studies |journal=Conservation Biology |date=1992 |volume=6 |issue=3 |pages=376–391 |jstor=2386038 |doi=10.1046/j.1523-1739.1992.06030376.x|bibcode=1992ConBi...6..376P }}</ref> According to the habitats, many other groups such as the rove beetles in human-modified habitats, dung beetles in savannas<ref>{{cite journal |doi=10.1046/j.1365-2664.2002.00743.x |title=The verification and application of bioindicators: A case study of dung beetles in a savanna ecosystem |journal=Journal of Applied Ecology |volume=39 |issue=4 |pages=661–672 |year=2002 |last1=McGeoch |first1=Melodie A. |last2=Van Rensburg |first2=Berndt J. |last3=Botes |first3=Antoinette|bibcode=2002JApEc..39..661M }}</ref> and saproxylic beetles in forests<ref>{{cite journal |doi=10.1016/j.ecolind.2012.04.013|title=Saproxylic beetles as indicator species for dead-wood amount and temperature in European beech forests |journal=Ecological Indicators |volume=23 |pages=323–331 |year=2012 |last1=Lachat |first1=Thibault |last2=Wermelinger |first2=Beat |last3=Gossner |first3=Martin M. |last4=Bussler |first4=Heinz |last5=Isacsson |first5=Gunnar |last6=Müller |first6=Jörg|bibcode=2012EcInd..23..323L }}</ref> have been suggested as potential indicator species.<ref>{{cite journal |doi=10.1016/S0167-8809(99)00043-2 |title=Staphylinid beetles as bioindicators |journal=Agriculture, Ecosystems & Environment |volume=74 |issue=1–3 |pages=357–372 |year=1999 |last1=Bohac |first1=Jaroslav|bibcode=1999AgEE...74..357B |url=http://www.zin.ru/animalia/coleoptera/pdf/bohac_1999_357-372.pdf |archive-url=https://web.archive.org/web/20170811032854/http://www.zin.ru/Animalia/Coleoptera/pdf/bohac_1999_357-372.pdf |archive-date=2017-08-11 |url-status=live |citeseerx=10.1.1.496.4273 }}</ref>

===In art and adornment===
{{Main|Beetlewing|Live insect jewelry}}
[[File:Zopheridae jewelry sjh.jpg|thumb|[[Zopheridae]] in [[jewellery]] at the [[Texas A&M University]] Insect Collection]]
[[File:Pendant watch in shape of beetle Switzerland 1850-1900 gold, diamond, enamel.jpg|thumb|Pendant watch in shape of beetle, Switzerland 1850–1900 gold, diamond, enamel|left|225x225px]]

Many beetles have durable elytra that has been used as material in art, with [[beetlewing]] the best example.<ref>{{usurped|1=[https://archive.today/20081022121229/http://www.malaeng.com/blog/?p=4262 Life cycle of the rounded jewel beetles, Sternocera spp. วงจรชีวิตของแมลงทับกลมใช้เวลานานถึง 2 ปี – Siam Insect Zoo-Museum]}}. Malaeng.com (2008-10-20). Retrieved on 2013-04-04.</ref> Sometimes, they are incorporated into ritual objects for their religious significance. Whole beetles, either as-is or encased in clear plastic, are made into objects ranging from cheap souvenirs such as key chains to expensive fine-art jewellery. In parts of Mexico, beetles of the genus ''[[Zopherus]]'' are made into [[living brooch]]es by attaching costume jewelry and golden chains, which is made possible by the incredibly hard elytra and sedentary habits of the genus.<ref name="Ivie">{{cite book |chapter=105. Zopheridae |author=Ivie, Michael A. |pages=[https://archive.org/details/americanbeetlesv00jr/page/n471 457]–462 |title=American Beetles: Polyphaga: Scarabaeoidea through Curculionoidea |url=https://archive.org/details/americanbeetlesv00jr |url-access=limited |series=Volume 2 of American Beetles |editor1=Ross H. Arnett |editor2=Michael Charles Thomas |publisher=[[CRC Press]] |year=2002 |isbn=978-0-8493-0954-0}}</ref>

===In entertainment===
Fighting beetles are used [[insect fighting|for entertainment and gambling]]. This sport exploits the territorial behavior and mating competition of certain species of large beetles. In the [[Chiang Mai]] district of northern Thailand, male ''[[Xylotrupes]]'' rhinoceros beetles are caught in the wild and trained for fighting. Females are held inside a log to stimulate the fighting males with their pheromones.<ref>{{cite journal |last1=Rennesson |first1=Stephane|last2=Cesard |first2=Nicolas |last3=Grimaud |first3=Emmanuel |title=Duels en miniature: la délicate mise en scène des combats de scarabées au nord de la Thaïlande |url=http://www7.inra.fr/opie-insectes/pdf/i151-renesson-et-al.pdf |archive-url=https://web.archive.org/web/20100821174942/http://www.inra.fr/opie-insectes/pdf/i151-renesson-et-al.pdf |archive-date=2010-08-21 |url-status=live |journal=Insectes |volume=3 |issue=151 |year=2008 | language=fr}}</ref> These fights may be competitive and involve gambling both money and property.<ref name='Costa-Neto'>{{cite journal |author1=Eraldo Medeiros Costa-Neto |title=Entertainment with insects: singing and fighting insects around the world. A brief review |journal=Etnobiología |volume=3 |pages=21–29 |date=2003 |url=https://dialnet.unirioja.es/descarga/articulo/5294425.pdf |access-date=January 30, 2021 }}</ref> In [[South Korea]] the [[Dytiscidae]] species ''[[Cybister tripunctatus]]'' is used in a roulette-like game.<ref>{{cite journal |author1=Pemberton, R. W. |title=The Korean water beetle game |journal=Pan-Pacific Entomologist |date=1990 |volume=66 |issue=2 |pages=172–174}}</ref>

Beetles are sometimes used as instruments: the Onabasulu of [[Papua New Guinea]] historically used the "[[Hugu (instrument)|''hugu'']]" weevil ''[[Rhynchophorus ferrugineus]]'' as a musical instrument by letting the human mouth serve as a variable [[resonance chamber]] for the wing vibrations of the live adult beetle.<ref name='Costa-Neto'/>

===As pets===
Some species of beetle are kept as [[pet]]s, for example diving beetles ([[Dytiscidae]]) may be kept in a domestic fresh water tank.<ref>{{cite web |url=https://edis.ifas.ufl.edu/pdffiles/FR/FR39800.pdf |archive-url=https://web.archive.org/web/20170202054428/https://edis.ifas.ufl.edu/pdffiles/FR/FR39800.pdf |archive-date=2017-02-02 |url-status=live |title=Predaceous Diving Beetles as Pets and the Self-Cleaning Aquarium |author1=Bateman, C. |author2=Hulcr, J. |date=2016 |publisher=[[University of Florida]] (IFAS Extension) |access-date=January 27, 2017 }}</ref>

[[File:Malay Archipelago Beetles.jpg|thumb|"Remarkable Beetles Found at Simunjon, Borneo".{{efn|The plate was labelled "Neocerambyx æneas, Cladognathus tarandus, Diurus furcellatus, Ectatorhinus Wallacei, Megacriodes Saundersii, Cyriopalpus Wallacei".}} A few of the 2,000 species of beetle collected by [[Alfred Russel Wallace]] in [[Borneo]]]]

In [[Japan]] the practice of keeping horned rhinoceros beetles ([[Dynastinae]]) and stag beetles ([[Lucanidae]]) is particularly popular amongst young boys.<ref>{{cite journal |url=http://www.flmnh.ufl.edu/mcguire/kawahara/wp-content/uploads/2012/02/Kawahara_2007_Am_Ent_sm.pdf |title=Thirty-foot telescopic nets, bug-collecting video games, and beetle pets: Entomology in modern Japan |author=Kawahara, A. Y. |date=2007 |journal=American Entomologist |volume=53 |issue=3 |pages=160–172 |doi=10.1093/ae/53.3.160 |access-date=January 27, 2017 |archive-url=https://web.archive.org/web/20160412042904/http://www.flmnh.ufl.edu/mcguire/kawahara/wp-content/uploads/2012/02/Kawahara_2007_Am_Ent_sm.pdf |archive-date=April 12, 2016  }}</ref> Such is the popularity in Japan that [[vending machines]] dispensing live beetles were developed in 1999, each holding up to 100 stag beetles.<ref>{{cite news |last=May |first=Mitchell |date=July 11, 1999 |title=Yen For Bugs |newspaper=[[Chicago Tribune]] |url=https://www.chicagotribune.com/1999/07/11/yen-for-bugs/ |access-date=2017-01-27}}</ref><ref>{{cite news |last=Watts |first=Jonathan |date=August 11, 1999 |title=Vending machine beetles |url=https://www.theguardian.com/uk/1999/aug/11/jonathanwatts |newspaper=The Guardian |access-date=January 27, 2017}}</ref>

===As things to collect===
Beetle collecting became extremely popular in the [[Victorian era]].<ref>{{cite book |last1=Morse |first1=Deborah Denenholz |last2=Danahay |first2=Martin A. |title=Victorian Animal Dreams: Representations of Animals in Victorian Literature and Culture |url=https://books.google.com/books?id=2eRn_GqPbBoC&pg=PA5 |year=2007 |publisher=Ashgate Publishing |isbn=978-0-7546-5511-4 |page=5 |quote=the Victorian mania for beetle collecting}}</ref> The naturalist [[Alfred Russel Wallace]] collected (by his own count) a total of 83,200 beetles during the eight years described in his 1869 book ''[[The Malay Archipelago]]'', including 2,000 species new to science.<ref>{{cite book | title=The Malay Archipelago: The land of the orang–utan, and the bird of paradise. A narrative of travel, with sketches of man and nature | publisher=Macmillan | author=Wallace, Alfred Russel | year=1869 |author-link=Alfred Russel Wallace | edition=1 | pages=vii–xiv}}</ref>

===As inspiration for technologies===

{{Further|Biomimetics}}

Several coleopteran adaptations have attracted interest in [[biomimetics]] with possible commercial applications. The [[bombardier beetle]]'s powerful repellent spray has inspired the development of a fine mist spray technology, claimed to have a low carbon impact compared to aerosol sprays.<ref>[https://web.archive.org/web/20131213022851/http://www.swedishbiomimetics.com/biomimetics_folder.pdf Swedish Biomimetics: The μMist Platform Technology] (original URL = http://www.swedishbiomimetics.com/biomimetics_folder.pdf) (archive date = December 13, 2013)</ref> Moisture harvesting behavior by the Namib desert beetle (''[[Stenocara gracilipes]]'') has inspired a self-filling water bottle which utilises [[hydrophilic]] and [[hydrophobic]] materials to benefit people living in dry regions with no regular rainfall.<ref>{{cite news |url=https://www.bbc.co.uk/news/technology-20465982 |title=Namib Desert beetle inspires self-filling water bottle |work=BBC News |date=November 23, 2012}}</ref>

Living beetles have been used as [[cyborg#Animal cyborgs|cyborg]]s. A [[Defense Advanced Research Projects Agency]] funded project implanted electrodes into ''[[Mecynorhina torquata]]'' beetles, allowing them to be remotely controlled via a radio receiver held on its back, as proof-of-concept for surveillance work.<ref>{{cite magazine |url=https://www.technologyreview.com/s/411814/the-armys-remote-controlled-beetle/ |title=The Army's Remote-Controlled Beetle |last1=Singer |first1=Emily |date=2009-01-29 |magazine=MIT Technology Review |access-date=2017-03-16}}</ref> Similar technology has been applied to enable a human operator to control the free-flight steering and walking gaits of ''[[Mecynorhina torquata]]'' as well as graded turning, backward walking and feedback control of ''[[Zophobas morio]]''.<ref>{{cite journal |title=Insect–computer hybrid legged robot with user-adjustable speed, step length and walking gait |last1=Cao |first1=Feng |last2=Zhang |first2=Chao |author3=Hao Yu Choo |last4=Sato |first4=Hirotaka |journal=Journal of the Royal Society Interface |date=2016 |volume=13 |issue=116 |article-number=20160060 |doi=10.1098/rsif.2016.0060|pmid=27030043 |pmc=4843679 }}</ref><!--<ref>{{cite journal |last1=Sato |first1=Hirotaka |last2=Doan |first2=Tat Thang Vo |last3=Kolev |first3=Svetoslav |last4=Huynh |first4=Ngoc Anh |last5=Zhang |first5=Chao |last6=Massey |first6=Travis L. |last7=Kleef |first7=Joshua van |last8=Ikeda |first8=Kazuo |author9-link=Pieter Abbeel |last9=Abbeel |first9=Pieter |date=2015-03-16 |title=Deciphering the Role of a Coleopteran Steering Muscle via Free Flight Stimulation |journal=Current Biology |volume=25 |issue=6 |pages=798–803 |doi=10.1016/j.cub.2015.01.051|pmid=25784033 |doi-access=free |bibcode=2015CBio...25..798S }}</ref>--><!--<ref>{{cite journal |last1=Vo Doan |first1=Tat Thang |last2=Tan |first2=Melvin Y.W. |last3=Bui |first3=Xuan Hien |last4=Sato |first4=Hirotaka |date=2017-11-03 |title=An Ultralightweight and Living Legged Robot |journal=Soft Robotics |volume=5 |issue=1 |pages=17–23 |doi=10.1089/soro.2017.0038|pmid=29412086 }}</ref>--><!--<ref>{{Cite journal |last1=Nguyen |first1=H. Duoc |last2=Dung |first2=V. Than |last3=Sato |first3=Hirotaka |last4=Vo-Doan |first4=T. Thang |date=2023-02-01 |title=Efficient autonomous navigation for terrestrial insect-machine hybrid systems |url=https://www.sciencedirect.com/science/article/abs/pii/S0925400522016318 |journal=Sensors and Actuators B: Chemical |volume=376 |article-number=132988 |doi=10.1016/j.snb.2022.132988 |issn=0925-4005|arxiv=2204.13281 |bibcode=2023SeAcB.37632988N }}</ref>--><ref>{{Cite journal |last1=Vo-Doan |first1=T. Thang |last2=Dung |first2=V. Than |last3=Sato |first3=Hirotaka |date=January 2022 |title=A Cyborg Insect Reveals a Function of a Muscle in Free Flight |journal=Cyborg and Bionic Systems |volume=2022 |article-number=2022/9780504 |doi=10.34133/2022/9780504 |pmc=9494732 |pmid=36285304}}</ref>

=== In conservation ===

Since beetles form such a large part of the world's biodiversity, their conservation is important, and equally, loss of habitat and biodiversity is essentially certain to impact on beetles. Many species of beetles have very specific habitats and long life cycles that make them vulnerable. Some species are highly threatened while others are already feared extinct.<ref>{{Cite journal |last1=Kotze |first1=D. Johan |last2=O'Hara |first2=Robert B. |date=2003 |title=Species decline—but why? Explanations of carabid beetle (Coleoptera, Carabidae) declines in Europe |journal=Oecologia |volume=135 |issue=1 |pages=138–148 |doi=10.1007/s00442-002-1174-3|pmid=12647113 |bibcode=2003Oecol.135..138K |s2cid=11692514 }}</ref> Island species tend to be more susceptible as in the case of ''Helictopleurus undatus'' of Madagascar which is thought to have gone extinct during the late 20th century.<ref>{{Cite journal |last1=Hanski |first1=Ilkka |last2=Koivulehto |first2=Helena |last3=Cameron |first3=Alison |last4=Rahagalala |first4=Pierre |date=2007 |title=Deforestation and apparent extinctions of endemic forest beetles in Madagascar |journal=Biology Letters |volume=3 |issue=3 |pages=344–347 |doi=10.1098/rsbl.2007.0043 |pmc=1995085 |pmid=17341451}}</ref> Conservationists have attempted to arouse a liking for beetles with flagship species like the stag beetle, ''[[Lucanus cervus]]'',<ref>{{cite journal |last1=Campanaro |first1=A. |author2=Zapponi, L. |author3=Hardersen, S. |author4=Méndez, M. |author5=Al Fulaij, N. |author6=Audisio, P. |author7=Bardiani, M. |author8=Carpaneto, G. M. |author9=Corezzola, S. |author10=Della Rocca, F. |author11=Harvey, D. |author12=Hawes, C. |author13=Kadej, M. |author14=Karg, J. |author15=Rink, M. |author16=Smolis, A. |author17=Sprecher, E. |author18=Thomaes, A. |author19=Toni, I. |author20=Vrezec, A. |author21=Zauli, A. |author22=Zilioli, M. |author23=Chiari, S. |display-authors=5 |date=2016 |title=A European monitoring protocol for the stag beetle, a saproxylic flagship species |journal=Insect Conservation and Diversity |volume=9 |issue=6 |pages=574–584 |doi=10.1111/icad.12194 |s2cid=88754595 }}</ref> and tiger beetles ([[Cicindelidae]]). In Japan the Genji firefly, ''[[Luciola cruciata]]'', is extremely popular, and in South Africa the Addo elephant dung beetle offers promise for broadening [[ecotourism]] beyond the [[big five game|big five tourist mammal species]]. Popular dislike of pest beetles, too, can be turned into public interest in insects, as can unusual ecological adaptations of species like the fairy shrimp hunting beetle, [[Cicindis|''Cicindis bruchi''.]]<ref>{{cite book |last=New |first=T. R. |title=Beetles in Conservation |url=https://books.google.com/books?id=44uv6YiZH4YC&pg=PR4 |year=2009|publisher=John Wiley & Sons |isbn=978-1-4443-1863-0 |pages=ix, 1–26, passim}}</ref><ref>{{Cite journal |last1=Erwin |first1=Terry L. |last2=Aschero |first2=Valeria |date=2004-06-28 |title=Cicindis horni Bruch (Coleoptera: Carabidae, Cicindini): The Fairy Shrimp Hunting Beetle, its way of life on the Salinas Grandes of Argentina |url=https://mapress.com/zt/article/view/zootaxa.553.1.1 |journal=Zootaxa |volume=553 |issue=1 |doi=10.11646/zootaxa.553.1.1}}</ref>

==Notes==
{{Notelist}}

==See also==
*[[Beetle Monuments]]

==References==
{{Reflist}}

===Bibliography===
{{refbegin}}
* {{cite book|last=Evans|first=Arthur V.|author2=Bellamy, Charles|year=2000|title=An Inordinate Fondness for Beetles|publisher=[[University of California Press]]|isbn=978-0-520-22323-3|url=https://books.google.com/books?id=ZZ_hfpMo8oAC&pg=PA31|ref=refEvans}}
* {{cite book|last1=McHugh|first1=Joseph V.|last2=Liebherr|first2=James K.|year=2009|chapter=Coleoptera|editor=Vincent H. Resh|editor2=Ring T. Cardé|pages=[https://archive.org/details/encyclopediainse00resh_059/page/n219 183]–201|title=Encyclopedia of Insects|url=https://archive.org/details/encyclopediainse00resh_059|url-access=limited|edition=2nd|publisher=Academic Press|isbn=978-0-12-374144-8|ref=refMcHugh}}
{{refend}}

==Further reading==

* {{cite book|author=Beckmann, Poul|title=Living Jewels: The Natural Design of Beetles|isbn=978-3-7913-2528-6|year=2001|publisher=Prestel |ref=none}}
* {{cite book|editor=Cooter, J.|editor2=[[Max Barclay|M. V. L. Barclay]]|year=2006|title=A Coleopterist's Handbook|publisher=Amateur Entomological Society|isbn=978-0-900054-70-9 |ref=none}}
* {{cite book|title=Beetle Larvae of the World|date=December 1994|publisher=[[Entomological Society of America]]|isbn=978-0-643-05506-3 |ref=none}}
* {{cite book|author=Grimaldi, David|author2=Michael S. Engel|title=Evolution of the Insects|isbn=978-0-521-82149-0|date=2005-05-16|publisher=Cambridge University Press |author2-link=Michael S. Engel|author-link=David Grimaldi (entomologist) |ref=none}}
* {{cite book|author=Harde, K. W.|title=A Field Guide in Color to Beetles|isbn=978-0-7064-1937-5|pages=7–24|year=1984|publisher=Octopus Books  |ref=none}}
* {{cite book|author=White, R. E.|year=1983|title=Beetles|publisher=Houghton Mifflin|isbn=978-0-395-91089-4|url=https://archive.org/details/isbn_9780395910894 |ref=none}}

==External links==
{{Wikispecies|Coleoptera}}
{{Wikibooks|Dichotomous Key|Coleoptera}}
* [http://tolweb.org/Coleoptera/8221 Coleoptera] from the [[Tree of Life Web Project]]
* {{in lang|de}} [https://www.kaefer-der-welt.de/index.htm ''Käfer der Welt'']
* [http://www.coleoptera-atlas.com/ Coleoptera Atlas] {{Webarchive|url=https://web.archive.org/web/20140106113024/http://www.coleoptera-atlas.com/ |date=January 6, 2014 }}
* [https://web.archive.org/web/20120313193822/http://www.insectlifeforms.com/Orders736/BEETLES_COLEOPTERA_60502060_736.aspx Beetles – Coleoptera]

{{Orders of Insects}}
{{Coleoptera}}
{{Insects in culture}}
{{Taxonbar|from=Q22671}}
{{Authority control}}

[[Category:Beetles| ]]
[[Category:Extant Pennsylvanian first appearances]]
[[Category:Insects in culture]]