Editing Lepidoptera (section)

=== Life cycle ===

[[File:Anise Swallowtail Life Cycle.svg|thumb|left|The four stages of the life cycle of an [[anise swallowtail]]]]

==== Eggs ====

Lepidoptera usually reproduce sexually and are [[oviparous]] (egg-laying), though some species exhibit live birth in a process called [[ovoviviparity]]. A variety of differences in [[egg]]-laying and the number of eggs laid occur. Some species simply drop their eggs in flight (these species normally have polyphagous larvae, meaning they eat a variety of plants e. g., [[hepialid]]s and some [[Nymphalidae|nymphalids]])<ref name="Wiklund">{{Cite journal |last=Wiklund |first=Christer |date=July 1984 |title=Egg-laying patterns in butterflies in relation to their phenology and the visual apparency and abundance of their host plants |journal=[[Oecologia]] |volume=63 |issue=1 |pages=23–29|doi=10.1007/BF00379780|pmid=28311161 |bibcode=1984Oecol..63...23W |s2cid=29210301 }}</ref> while most lay their eggs near or on the host plant on which the larvae feed. The number of eggs laid may vary from only a few to several thousand.<ref name="cgillott"/> The females of both butterflies and moths select the host plant instinctively, and primarily, by chemical cues.<ref name="Resh and Carde"/>{{Rp|564}}

The eggs are derived from materials ingested as a larva and in some species, from the spermatophores received from males during mating.<ref>{{cite book |last1=Oberhauser |first1=Karen S. |author-link1=Karen Oberhauser |last2=Solensky |first2=Michelle J |title=The Monarch Butterfly: Biology and Conservation |year=2004 |publisher=Cornell University Press |location=Ithaca NY |isbn=978-0801441882 |edition=First |ref={{harvid|Oberhauser2004}} |url=https://archive.org/details/monarchbutterfly00mich }}</ref> An egg can only be 1/1000 the mass of the female, yet she may lay up to her own mass in eggs. Females lay smaller eggs as they age. Larger females lay larger eggs.{{sfn|Oberhauser|2004|p=24}} The egg is covered by a hard-ridged protective outer layer of shell, called the [[chorion]]. It is lined with a thin coating of [[wax]], which prevents the egg from drying out. Each egg contains a number of [[micropyle (zoology)|micropyles]], or tiny funnel-shaped openings at one end, the purpose of which is to allow sperm to enter and fertilize the egg. Butterfly and moth eggs vary greatly in size between species, but they are all either spherical or ovate.

The egg stage lasts a few weeks in most butterflies, but eggs laid prior to winter, especially in [[temperate region]]s, go through [[diapause]], and hatching may be delayed until spring. Other butterflies may lay their eggs in the spring and have them hatch in the summer. These butterflies are usually temperate species (e. g. ''[[Nymphalis antiopa]]'').

==== Larvae ====
{{Main|Caterpillar}}
[[File:Arctiidae caterpillar edit.jpg|thumb|upright|right|Larval form typically lives and feeds on plants]]

The larvae or caterpillars are the first stage in the life cycle after hatching. Caterpillars are "characteristic [[Wiktionary:polypod|polypod]] larvae with cylindrical bodies, short thoracic legs, and abdominal prolegs (pseudopods)".<ref name="Gullan_Cranston_2010">{{cite book |author1=Gullan, P. J.  |author2=Cranston, P. S. |year=2010|title=The Insects: an Outline of Entomology |edition=4th |isbn=978-1-4443-3036-6|publisher=[[Wiley-Blackwell]]|chapter=Life-history patterns and phases |pages=156–164}}</ref> They have a sclerotized head capsule with an adfrontal suture formed by medial fusion of the sclerites, [[Mandible (insect mouthpart)|mandibles (mouthparts)]] for chewing, and a soft tubular, segmented body, that may have hair-like or other projections, three pairs of true legs, and additional [[proleg]]s (up to five pairs).<ref name="Dugdale"/> The body consists of thirteen segments, of which three are thoracic and ten are abdominal.<ref name="Triplehorn & Johnson (2005)">{{cite book |title=Borror and Delong's Introduction to the Study of Insects |last=Triplehorn |first=Charles A.|author2=Johnson, Norman F.  |year=2005 |publisher=Thomson Brooks/Cole |location=Belmont, California|isbn=978-0-03-096835-8 |url=https://books.google.com/books?id=_uFkQgAACAAJ}}</ref> Most larvae are [[herbivore]]s, but a few are [[carnivore]]s (some eat ants or other caterpillars) and [[detritivore]]s.<ref name="Dugdale">{{cite journal |last1=Dugdale |first1=J. S. |year=1996 |title=Natural history and identification of litter-feeding Lepidoptera larvae (Insecta) in beech forests, Orongorongo Valley, New Zealand, with especial reference to the diet of mice (''Mus musculus'') |journal=Journal of the Royal Society of New Zealand |volume=26 |issue=4 |pages=251–274 |url=http://www.royalsociety.org.nz/media/publications-journals-nzjr-1996-058.pdf |doi=10.1080/03014223.1996.9517513 |bibcode=1996JRSNZ..26..251D |access-date=14 November 2010 }}{{dead link|date=December 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

Different herbivorous species have adapted to feed on every part of the plant and are normally considered pests to their host plants; some species have been found to lay their eggs on the fruit and other species lay their eggs on clothing or fur (e. g., ''[[Tineola bisselliella]]'', the common clothes moth). Some species are carnivorous, and others are even parasitic. Some [[lycaenid]] species such as ''[[Phengaris rebeli]]'' are [[social parasitism (biology)|social parasites]] of ''[[Myrmica]]'' ant nests.<ref>{{cite journal |last1=Elmes |first1=G.W. |last2=Wardlaw |first2=J.C. |last3=Schönrogge |first3= K. |last4= Thomas |first4= J.A. |last5=Clarke |first5=R.T. |title=Food stress causes differential survival of socially parasitic caterpillars of Maculinea rebeli integrated in colonies of host and non-host Myrmica ant species
 |journal=Entomologia Experimentalis et Applicata |volume=110 |issue=1 |pages=53–63 |doi= 10.1111/j.0013-8703.2004.00121.x|year=2004 |bibcode=2004EEApp.110...53E |s2cid=86427983 }}</ref> A species of [[Geometridae]] from [[Hawaii]] has carnivorous larvae that catch and eat flies.<ref name=autogenerated4>{{Cite book|last=Arnett|first=Ross H. Jr.|title=American Insects. A Handbook of the Insects of America North of Mexico|publisher=CRC press LLC|date=28 July 2000|edition=2|pages=631–632|isbn=978-0-8493-0212-1|url=https://books.google.com/books?id=4M0v0Ye54MYC&q=lepidopera|access-date=8 October 2020|archive-date=31 May 2021|archive-url=https://web.archive.org/web/20210531113739/https://books.google.com/books?id=4M0v0Ye54MYC&q=lepidopera|url-status=live}}</ref> Some pyralid caterpillars are aquatic.<ref>{{Cite journal |author=Berg, Clifford O. |year=1950 |title=Biology of certain aquatic caterpillars (Pyralididae: ''Nymphula'' spp.) which feed on ''Potamogeton'' |journal=Transactions of the American Microscopical Society |volume=69 |issue=3 |pages=254–266 |jstor=3223096 |doi=10.2307/3223096}}</ref>

The larvae develop rapidly with several generations in a year; however, some species may take up to 3 years to develop, and exceptional examples like ''[[Gynaephora groenlandica]]'' take as long as seven years.<ref name="cgillott"/> The larval stage is where the feeding and growing stages occur, and the larvae periodically undergo hormone-induced [[ecdysis]], developing further with each [[instar]], until they undergo the final larval-pupal molt.

The larvae of both butterflies and moths exhibit mimicry to deter potential predators. Some caterpillars have the ability to inflate parts of their heads to appear snake-like. Many have false eye-spots to enhance this effect. Some caterpillars have special structures called [[osmeteria]] (family [[Papilionidae]]), which are exposed to produce smelly chemicals used in defense. Host plants often have toxic substances in them, and caterpillars are able to sequester these substances and retain them into the adult stage. This helps make them unpalatable to birds and other predators. Such unpalatability is advertised using bright red, orange, black, or white warning colors. The toxic chemicals in plants are often evolved specifically to prevent them from being eaten by insects. Insects, in turn, develop countermeasures or make use of these toxins for their own survival. This "arms race" has led to the coevolution of insects and their host plants.<ref>{{cite journal | doi = 10.2307/2406212 | last1 = Ehrlich | first1 = P. R. | last2 = Raven | first2 = P. H. | year = 1964 | title = Butterflies and plants: a study in coevolution| journal = Evolution | volume = 18 | issue = 4| pages = 586–608 | jstor = 2406212}}</ref>

==== Wing development ====

No form of wing is externally visible on the larva, but when larvae are dissected, developing wings can be seen as disks, which can be found on the second and third thoracic segments, in place of the spiracles that are apparent on abdominal segments. Wing disks develop in association with a trachea that runs along the base of the wing, and are surrounded by a thin peripodial membrane, which is linked to the outer epidermis of the larva by a tiny duct. Wing disks are very small until the last larval instar, when they increase dramatically in size, are invaded by branching [[Invertebrate trachea|tracheae]] from the wing base that precede the formation of the wing veins and begin to develop patterns associated with several landmarks of the wing.<ref name="Nijhout">{{Cite book |last=Nijhout |first=H. Frederik |title=The Development and Evolution of Butterfly Wing Patterns(Smithsonian Series in Comparative Evolutionary Biology) |publisher=Smithsonian Institution Scholarly Press |date=17 August 1991 |edition=1 |pages=2–4 |isbn=978-0-87474-917-5 |url=https://books.google.com/books?id=4M0v0Ye54MYC&q=lepidopera |access-date=8 October 2020 |archive-date=31 May 2021 |archive-url=https://web.archive.org/web/20210531113739/https://books.google.com/books?id=4M0v0Ye54MYC&q=lepidopera |url-status=live }}</ref>

Near pupation, the wings are forced outside the epidermis under pressure from the [[hemolymph]], and although they are initially quite flexible and fragile, by the time the pupa breaks free of the larval cuticle, they have adhered tightly to the outer cuticle of the pupa (in obtect pupae). Within hours, the wings form a cuticle so hard and well-joined to the body that pupae can be picked up and handled without damage to the wings.<ref name="Nijhout"/>

==== Pupa ====

[[File:Papilio dardanus emerging.ogv|left|thumb|Eclosion of ''[[Papilio dardanus]]'']]

After about five to seven instars,<ref name="Dole">{{Cite book |last=Dole |first=Claire Hagen |title=The Butterfly Gardener's Guide |publisher=Brooklyn Botanic Garden |date=28 May 2003|isbn=978-1-889538-58-7 |url=https://archive.org/details/butterflygardene00clai|url-access=registration |page=[https://archive.org/details/butterflygardene00clai/page/26 26] |quote=metamorphosis butterfly. }}</ref>{{rp|26–28}} or molts, certain hormones, like PTTH, stimulate the production of [[ecdysone]], which initiates insect molting. The larva starts to develop into the [[pupa]]: body parts specific to the larva, such as the abdominal prolegs, degenerate, while others such as the legs and wings undergo growth. After finding a suitable place, the animal sheds its last larval cuticle, revealing the pupal cuticle underneath.

Depending on the species, the pupa may be covered in a silk cocoon, attached to different types of substrates, buried in the ground, or may not be covered at all. Features of the [[imago]] are externally recognizable in the pupa. All the appendages on the adult head and thorax are found cased inside the cuticle ([[antenna (biology)|antenna]]e, [[Insect mouthparts|mouthpart]]s, etc.), with the wings wrapped around, adjacent to the antennae.<ref name="Resh and Carde"/>{{Rp|564}} The pupae of some species have functional mandibles, while the pupal mandibles are not functional in others.<ref name="scoble_heads" />

Although the pupal cuticle is highly sclerotized, some of the lower abdominal segments are not fused, and are able to move using small muscles found in between the membrane. Moving may help the pupa, for example, escape the sun, which would otherwise kill it. The pupa of the [[Mexican jumping bean]] moth (''[[Cydia saltitans]]'') does this. The larvae cut a trapdoor in the bean (species of ''[[Sebastiania]]'') and use the bean as a shelter. With a sudden rise in temperature, the pupa inside twitches and jerks, pulling on the threads inside. Wiggling may also help to deter [[parasitoid]] wasps from laying eggs on the pupa. Other species of moths are able to make clicks to deter predators.<ref name="Resh and Carde"/>{{Rp|564, 566}}

The length of time before the pupa ecloses (emerges) varies greatly. The monarch butterfly may stay in its chrysalis for two weeks, while other species may need to stay for more than 10 months in diapause. The adult emerges from the pupa either by using abdominal hooks or from projections located on the head. The mandibles found in the most primitive moth families are used to escape from their cocoon (e. g., [[Micropterigoidea]]).<ref name="cgillott"/><ref name="Resh and Carde"/>{{Rp|564}}

==== Adult ====

Most lepidopteran species do not live long after eclosion, only needing a few days to find a mate and then lay their eggs. Others may remain active for a longer period (from one to several weeks) or go through diapause and overwintering as monarch butterflies do, or waiting out environmental stress. Some adult species of microlepidoptera go through a stage where no reproductive-related activity occurs, lasting through summer and winter, followed by mating and oviposition in the early spring.<ref name="Resh and Carde"/>{{Rp|564}}

While most butterflies and moths are [[Terrestrial animal|terrestrial]], many species of [[Acentropinae]] ([[Crambidae]]) are truly [[Aquatic animal|aquatic]] with all stages except the adult occurring in water. Many species from other families such as [[Erebidae]], [[Nepticulidae]], [[Cosmopterigidae]], [[Tortricidae]], [[Olethreutidae]], [[Noctuidae]], [[Cossidae]], and [[Sphingidae]] are aquatic or [[:wikt:semi-aquatic|semiaquatic]].<ref name="Ward">{{cite book |author1=Ward, James V. |author2=Ward, Peter E. |year=1992 |title=Aquatic Insect Ecology, Biology And Habitat |publisher=John Wiley & Sons |isbn=978-0-471-55007-5}}</ref>{{rp|22}}

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