The standard progression of insects from egg, through feeding growing larva, metamorphosing chrysalis, and finally to fully winged adult, is not quite universal.
Batflies (genus Ascodipteron; family Streblidae) have taken this further – or backwards, depending on your point of view. When a female batfly emerges from her pupa on the floor of a bat roo in a cave or hollow tree, she mates and flies up to locate a host.
She then sheds her wings, burrows under the bat’s skin and starts to revert to a maggot-like form, losing much of the obvious head-thorax-abdomen segmentation seen in most adult insects.
She feeds on bat blood, nourishing a single larva inside her abdomen, in a body cavity analogous to a womb. When the larva is fully grown, it is released, drops to the roost floor and pupates. Unlike most other insect larvae it does not feed or grow independently.
This is an extreme retrogression, but several other blood-sucking flies also lose their wings when they start living in their host’s fur, and queen ants famously shed their wings after a mating flight so they can found a new colony underground.
Main image © B. Jobling, Public domain, via Wikimedia Commons
