Simplest insect

In terms of morphological degeneration, the simplest insects are the wingless and limbless adult females of the Malaysian phorid fly Vestigipoda longiseta, which very closely resemble the grub-like larvae of Aenictus ants and live inside these ants' nests, where they are cared for by the ants who mistakenly assume that they are their own larvae because of their great external similarity.

It is interesting to note that adult male specimens of this highly unusual species of fly have yet to be conclusively identified. Yet unless they too exhibit this profound degree of parasitism-driven morphological degeneration exhibited by the adult females, it is difficult to know how such males would be recognized anyway. For if they resembled normal adult male flies belonging to allied genera, there would be no obvious clues that they were in any way related taxonomically to the ant-larva-like females.