Editing Butterfly (section)

====Pupa====

[[File:Chrysalis5504.jpg|thumb|upright|[[Chrysalis]] of [[gulf fritillary]]]]

When the larva is fully grown, hormones such as [[prothoracicotropic hormone]] (PTTH) are produced. At this point the larva stops feeding, and begins "wandering" in the quest for a suitable pupation site, often the underside of a leaf or other concealed location. There it spins a button of silk which it uses to fasten its body to the surface and moults for a final time. While some caterpillars spin a [[Pupa#Cocoon|cocoon]] to protect the pupa, most species do not. The naked pupa, often known as a chrysalis, usually hangs head down from the cremaster, a spiny pad at the posterior end, but in some species a silken girdle may be spun to keep the pupa in a head-up position.<ref name=Capinera640/> Most of the tissues and cells of the larva are broken down inside the pupa, as the constituent material is rebuilt into the imago. The structure of the transforming insect is visible from the exterior, with the wings folded flat on the ventral surface and the two halves of the proboscis, with the antennae and the legs between them.<ref name=Formfunction>{{cite encyclopedia |url=https://www.britannica.com/animal/lepidopteran/Form-and-function |title=Lepidopteran: Form and function |author=Culin, Joseph |encyclopedia=Encyclopædia Britannica |access-date=8 September 2015 |archive-date=21 September 2017 |archive-url=https://web.archive.org/web/20170921192451/https://www.britannica.com/animal/lepidopteran/Form-and-function |url-status=live }}</ref>

The pupal transformation into a butterfly through [[metamorphosis]] has held great appeal to mankind. To transform from the miniature wings visible on the outside of the pupa into large structures usable for flight, the pupal wings undergo rapid mitosis and absorb a great deal of nutrients. If one wing is surgically removed early on, the other three will grow to a larger size. In the pupa, the wing forms a structure that becomes compressed from top to bottom and pleated from proximal to distal ends as it grows, so that it can rapidly be unfolded to its full adult size. Several boundaries seen in the adult colour pattern are marked by changes in the expression of particular transcription factors in the early pupa.<ref name="pmid11676917">{{cite journal |author1=Brunetti, Craig R. |author2=Selegue, Jayne E. |author3=Monteiro, Antonia |author4=French, Vernon |author5=Brakefield, Paul M. |author6=Carroll, Sean B. |year=2001 |title=The Generation and Diversification of Butterfly Eyespot Color Patterns |journal=Current Biology |volume=11 |issue=20 |pages=1578–1585 |doi=10.1016/S0960-9822(01)00502-4 |pmid=11676917|s2cid=14290399 |doi-access=free |bibcode=2001CBio...11.1578B }}</ref>