Editing Lepidoptera (section)

==== 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"/>