Nymph (biology)

Two Schistocerca gregaria nymphs beside an adult

In biology, a nymph (from Ancient Greek νύμφα nūmphē meaning "bride") is the juvenile form of some invertebrates, particularly insects, which undergoes gradual metamorphosis (hemimetabolism) before reaching its adult stage.<ref>Encyclopedia of Entomology Ed. John L. Capinera. Dordrecht, London, Springer. 2008, 2nd Ed. Template:ISBN (Print) 978-1-4020-6359-6 (Online)</ref> Unlike a typical larva, a nymph's overall form already resembles that of the adult, except for a lack of wings (in winged species) and the emergence of genitalia. In addition, while a nymph moults, it never enters a pupal stage. Instead, the final moult results in an adult insect.<ref name=":0">Template:Cite journal</ref> Nymphs undergo multiple stages of development called instars.

Taxa with nymph stages

Ixodes scapularis adult and nymph, left and right.

Dragonfly nymphs are aquatic, unlike the adult form. (pictured: Aeshna grandis)

Many species of arthropods have nymph stages. This includes the insect orders such as Orthoptera (crickets, grasshoppers and locusts), Hemiptera (cicadas, shield bugs, whiteflies, aphids, leafhoppers, froghoppers, treehoppers), mayflies, termites, cockroaches, mantises, stoneflies and Odonata (dragonflies and damselflies).<ref>Template:Cite web</ref> Arachnids such as spiders, mites, and ticks also have nymphs.

Nymphs of aquatic insects, as in the Odonata, Ephemeroptera, and Plecoptera orders, are also called naiads, an Ancient Greek name for mythological water nymphs. Some entomologists have said that the terms larva, nymph and naiad<ref>Template:Cite journal</ref> should be used according to the developmental mode classification (hemimetabolous, paurometabolous or holometabolous) but others have pointed out that there is no real confusion.<ref>Template:Cite journal</ref> In older literature, these were sometimes referred to as the heterometabolous insects, as their adult and immature stages live in different environments (terrestrial vs. aquatic).<ref>Template:Cite journal</ref>

Second Egg Hypothesis

In 1628, English physician William Harvey published An Anatomical Disquisition on the Motion of the Heart and Blood in Animals. In his writing, Harvey hypothesized that the pupal stage in insects was the result of imperfect eggs.<ref name=":0" /> While some eggs produced smaller versions of fully-matured insects known as nymphs, others created intermediate forms. Thus, these intermediate forms must go through a second egg stage to reach their adult form. This hypothesis attempts to explain the developmental differences between hemimetabolous and holometabolous metamorphosis. Though an outdated hypothesis, it was still significant towards the modern understanding of nymphs.<ref>Template:Cite journal</ref>

Relationship with humans

The Pheasant Tail Nymph attracts trout by imitating a brown aquatic insect larva.

In fly fishing with artificial flies, this stage of aquatic insects is the basis for an entire series of representative patterns for trout.<ref>Template:Cite web</ref> They account for over half of the fishing fly patterns regularly used in the United States.

External links

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