Papilio glaucus
Template:Short description Template:Speciesbox
Papilio glaucus, the eastern tiger swallowtail, is a species of butterfly native to eastern North America. It is one of the most familiar butterflies in the eastern United States,<ref name=Cech>Template:Cite book</ref> ranging north to southern Ontario, Canada,<ref>Template:Cite web</ref> and is common in many different habitats. It flies from spring until fall, during which it produces two to three broods. Adults feed on the nectar of many species of flowers, mostly from those of the families Apocynaceae, Asteraceae, and Fabaceae. P. glaucus has a wingspan measuring Template:Convert. The male is yellow with four black "tiger stripes" on each forewing. Females may be either yellow or black, making the females dimorphic. The yellow morph has similar coloring to the male, but with a conspicuous band of blue spots along the hindwing; the dark morph is almost completely black.
The green eggs are laid singly on plants of the families Magnoliaceae and Rosaceae. Young caterpillars are brown and white; older ones are green with two black, yellow, and blue eyespots on the thorax. The caterpillar will turn brown prior to pupating. It will reach a length of Template:Convert. The chrysalis varies from a whitish color to dark brown. Hibernation occurs in this stage in locations with cold winter months.
The eastern tiger swallowtail is the state butterfly of Alabama (as well as state mascot),<ref>Template:Citation</ref> Delaware, Georgia, North Carolina and South Carolina,<ref name="statebutterflies">"Official State Butterflies Template:Webarchive." Netstate. NSTATE LLC. 26 June 2013. Retrieved 3 August 2013.</ref> and is the state insect of Virginia.<ref name=stateinsects>Template:Cite web</ref>
Description
The wingspan ranges from Template:Convert<ref name=Shull/> with females being the larger sex. Southern individuals are larger than northern ones.<ref name=clemson>Template:Cite web</ref> Males are yellow with four black "tiger stripes" on each forewing. The outer edge of the forewing is black with a row of yellow spots. The veins are marked with black. The postmedian area of the hindwing is black with yellow spots along the margin. The inner margin of the hindwing has small red and blue spots. The ventral forewing margin has a yellow bar that is broken into spots. This broken bar is present in both sexes, and is used to distinguish P. glaucus from its close relatives.<ref name=Brock>Template:Cite book</ref>
Females are dimorphic. The yellow morph differs from the male in having a blue postmedian area on the dorsal hindwing. In the dark morph, the areas that are normally yellow are replaced with dark gray or black. The bluish postmedian area on the ventral hindwing has one row of orange spots.<ref name=Glassberg/> A shadow of the "tiger stripes" can be seen on the underside of some dark females.<ref name=Brock/>
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Female dark morph upperside -
Female dark morph underside
P. glaucus is one of a few species of papilionids known to produce gynandromorphs. Most bilateral gynandromorphs are hybrids of P. glaucus and P. canadensis that are found along hybrid zones. Color mosaics are found in the central part of the species range.<ref name=Scriber>Template:Cite journal</ref>
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Eastern Tiger Swallowtail at the State Botanical Garden of Georgia
Taxonomy
The first known drawing of a North American butterfly was of an eastern tiger swallowtail. It was drawn by John White in 1587,<ref name=Cech/> during Sir Walter Raleigh's third expedition to Virginia.<ref name=ADW/> White named his drawing "Mamankanois" which is believed to be a Carolina Algonquian word for "butterfly".<ref>Template:Cite web</ref> This species was later described by Carl Linnaeus in his 10th edition of Systema Naturae in 1758.<ref name=taxonomicreport/> Some taxonomists place P. glaucus, along with the other tiger swallowtails, in the genus Pterourus.<ref name=Cech/>
The eastern tiger swallowtail was formerly considered a single species with a vast range into northern Canada and the eastern United States.<ref name=Cech/> In 1991, the subspecies Papilio glaucus canadensis was elevated to species level, thus reducing the range of P. glaucus to south of Canada.<ref name=lepsocjournal>Template:Cite journal</ref> In 2002, another closely related species, P. appalachiensis, was described by H. Pavulaan and D. M. Wright from the southern Appalachian Mountains.<ref name=taxonomicreport>Template:Cite journal</ref> These two species can be separated from P. glaucus by size; P. canadensis is smaller and P. appalachiensis is larger. These two also have a solid yellow bar along the margin of the ventral forewing.<ref name=Brock/> P. canadensis females are not dimorphic, and P. appalachiensis females are rarely black.<ref name=taxonomicreport2>Template:Cite journal</ref>
Similar species for the dark P. glaucus female include the pipevine swallowtail (Battus philenor), the spicebush swallowtail (Papilio troilus), and the female black swallowtail (Papilio polyxenes). B. philenor differs from the dark morph P. glaucus by the row of light-colored spots on each wing margin. P. troilus is more greenish, and has two rows of orange spots on the ventral hindwing. P. polyxenes is smaller, and the ventral hindwing has two rows of yellow-orange spots.<ref name=Brock/>
Distribution and habitat
P. glaucus is found in the eastern United States from southern Vermont to Florida west to eastern Texas and the Great Plains.<ref name=Cech/> It is common throughout its range,<ref name=Glassberg>Template:Cite book</ref> although is rarer in southern Florida and absent from the Florida Keys.<ref name=Cech/> In 1932, a single specimen was collected in County Wicklow, Ireland. It is believed to have been an accidental introduction from North America.<ref name=UKbutterflies>Template:Cite web</ref>
P. glaucus can be found almost anywhere deciduous forests occur. Common habitats include woodlands, fields, rivers, creeks, roadsides, and gardens. It will stray into urban parks and city yards.<ref name=Shull>Template:Cite book</ref><ref name=Iftner>Template:Cite book</ref><ref name=Nielson>Template:Cite book</ref> Because it has adapted to many different habitats and host plants, P. glaucus is a generalist, and is not considered threatened.<ref name=Cech/><ref name=ADW/> Papilio glaucus is considered to be one of the most polyphagous of all swallowtail species.<ref name="Scriber1991">Template:Cite journal</ref> This is likely due to genetic traits and differential detoxification abilities.<ref>Template:Cite journal in Scriber (1991) Template:Webarchive</ref> However, as compared to Papilio canadensis, at the northern overlap between the two species, P. glaucus survive very poorly through their first larval instar when settling on a quaking aspen (Populus tremeloides) tree and their survival rate under those conditions are approximately 15%, whereas P. canadensis thrives on this food plant.<ref name="Scriber1991"/>
Adults are seen from spring to fall, although the exact date varies depending on the location. In the south, they are seen from February to November; in the north, they are seen from May to September.<ref name=Cech/><ref name=Shull/><ref name=Iftner/> P. glaucus produces two broods in the north and three in the south. The first broods yield the smallest adults.<ref name=Cech/>
Behavior
Eastern tiger swallowtails are diurnal, and are usually solitary. Adults are known to fly high above the ground, usually seen above the tree canopy.<ref name=ADW>Template:Cite web</ref><ref name=Fullard>Template:Cite journal</ref> Males seek females by patrolling habitats containing the larval host plants. During courtship, the male and female fly about each other prior to landing and mating. The male releases perfume-like pheromones during courtship to entice the female into mating.<ref name=Cech/><ref name=Scott>Template:Cite book</ref>
Adults use a wide range of food sources, most preferring to nectar on sturdy plants with red or pink flowers.<ref name=Cech/><ref name=clemson/> Many members of the families Apocynaceae, Asteraceae and Fabaceae are used as common nectar sources.<ref name=Iftner/><ref name=Nielson/> Males participate in a behavior called puddling, in which they congregate on mud, damp gravel or puddles. They extract sodium ions and amino acids from these sources which aid in reproduction.<ref name=Iftner/><ref name=Lederhouse/> Males that puddle are typically fresh, and puddle only for their first couple of days. Females will occasionally puddle, but do not form congregations.<ref name=Lederhouse>Template:Cite journal</ref> Adults have also been seen feeding on dung, carrion, and urine.<ref name=Iftner/>
The eastern tiger swallowtail, Papilio glaucus, is probably the most polyphagous of all 560+ species of swallowtail butterflies in the world.<ref name=Scriber1991/>
Life cycle
The butterfly may have one or two generations in the north, while southern areas may have three. Time duration for various stages is as follows:
- Egg - It takes three to five days for eggs to hatch.
- Larva - The caterpillar has five instars.
- Pupa - The chrysalis stage lasts nine to eleven days, or over winter hibernation.
Egg
Females lay their eggs singly on the host plant leaves,<ref name=Scott/> preferring to oviposit on host plants near nectar sources.<ref name=Grossmueller>Template:Cite journal</ref> The egg is round and green, later turning yellowish green with reddish dots.<ref name=Scott/> The size of the egg is large for a butterfly, being 0.8 millimeters (0.03 in) in height and 1.2 millimeters (0.05 in) in width.<ref name=Pyle>Template:Cite book</ref> It takes between 4 and 10 days to hatch.<ref name=Stokes>Template:Cite book</ref>
Caterpillar
The caterpillar eats the leaves of the host plant. It will rest on a silk pad on a leaf, with the edges of the leaf folded over itself and held together with silk.<ref name=Scott/><ref name=Wagner>Template:Cite book</ref><ref name=naturalhistorynotes/> The first three instars are brown. A large white spot, known as a saddle, is found on the abdomen. After molting to the fourth instar, the caterpillar becomes green. The swollen thorax has two black, yellow, and blue eyespots. These eyespots are much smaller than those of the similar-looking spicebush swallowtail caterpillar. A yellow and black transverse stripe is present between the first and second abdominal segments. It is concealed between the folds of the segments when the caterpillar is at rest.<ref name=Scott/><ref name=Wagner/> The abdomen is spotted transversely with light blue. Before pupating, the caterpillar will turn dark brown. It will reach a length of Template:Convert. The caterpillar of P. glaucus is impossible to distinguish from the caterpillars of P. canadensis and P. appalachiensis.<ref name=Scott/><ref name=Wagner/>
Chrysalis
The chrysalis measures Template:Convert.<ref name=Pyle/> It hangs from a surface by a silk girdle around the thorax and a silk pad at the base.<ref name=Scott/> The chrysalis varies in color, ranging from off white to dark brown. It is often spotted with green and dark brown. Lighter-colored chrysalids often have a dark lateral stripe along each side of the body. Two horn-like projections are present on the head; one is found on the thorax. P. glaucus chrysalids can be found in a variety of places, but are commonly found on tree trunks, fence posts, and in ground litter.<ref name=Scott/> It hibernates in locations with cold winters.<ref name=Cech/>
Host plants
The caterpillar feeds on host plants of many different families.<ref name=Cech/> Common host plants used are those of the families Magnoliaceae and Rosaceae, with species including tulip tree (Liriodendron tulipifera), sweet bay magnolia (Magnolia virginiana) and wild black cherry (Prunus serotina).<ref name="TNC"/> It also feeds on other members of the family Rosaceae, as well as members from the families Lauraceae, Oleaceae, Rutaceae, and Tilioideae.<ref name=Shull/><ref name=Iftner/><ref name=Pyle/> Aspens (Populus sect. Populus), birches (Betula), and willows (Salix) have been recorded in older literature as host plants, but these are used by P. canadensis.<ref name=TNC/> Host plants of P. glaucus include:
- Wild black cherry (Prunus serotina)
- Ash (Fraxinus species)
- Cottonwood (Populus species)
- Wafer ash or hoptree (Ptelea trifoliata)
- Common lilac (Syringa vulgaris)
- Sweet bay magnolia (Magnolia virginiana)
- Tulip poplar or tulip tree (Liriodendron tulipifera)
- Willow (Salix species)<ref>Template:Cite book</ref>
Defense against predators
The first three instars of the caterpillar are bird dropping mimics, coloration that helps protect it from predators. In later instars, the eyespots on the thorax serve to deter birds.<ref name=naturalhistorynotes>Template:Cite web</ref> Like all members of the family Papilionidae, the caterpillar of P. glaucus possesses an osmeterium, an orange, fleshy organ that emits foul-smelling terpenes to repel predators. Normally hidden, the osmeterium is located on the first segment of the thorax, and can be everted when the caterpillar feels threatened.<ref name=Eisner>Template:Cite journal</ref> The combination of eyespots and osmeterium makes the caterpillar resemble a snake.<ref name=Grolier>Template:Cite web</ref>
Since adults are palatable, dark morph females use Batesian mimicry to protect themselves from vertebrate predators by mimicking the poisonous pipevine swallowtail. Dark morph females are more prevalent in the south, where B. philenor is more common.<ref name=Brock/><ref name=Hall>Template:Cite web</ref>
See also
References
Further reading
External links
- Pages with broken file links
- Papilio
- Butterflies described in 1758
- Butterflies of North America
- Animal taxa named by Carl Linnaeus
- Symbols of Georgia (U.S. state)
- Symbols of Alabama
- Symbols of North Carolina
- Symbols of South Carolina
- Symbols of Virginia
- Symbols of Delaware
- Lepidoptera of the United States
- Lepidoptera of Canada