Swift Feather-legged Fly

Appearance

This fly is about the size of a large housefly. It has a black head with large brown eyes, a mostly black thorax, a bright orange abdomen, transparent smoky wings with prominent veins, black legs and yellow feet. The hind legs bear a comb-like fringe of short hairs. Male flies have a dark spot on the wings and females have a dark tip to the abdomen.

Behavior

"Trichopoda pennipes" first appears in the late spring or early summer and feeds on nectar sucked from flowers such as Queen Anne's lace and meadowsweet. It may be seen hovering over other plants in search of suitable bugs on which to lay its eggs, most commonly squash bugs and southern green stinkbugs. The female fly lays several small, pale-coloured, oval eggs on a large nymph or an adult bug. When the eggs hatch, the larvae burrow into the bug. If there are several larvae in one host, only one survives. After feeding on the bug's tissues, the cream-coloured larva emerges and falls to the ground where it pupates in a reddish-brown puparium formed from the last larval skin. The bug meanwhile dies. After about two weeks, an adult fly emerges from the pupa. After mating, a female fly may lay several hundred eggs in total. There are up to three generations of the fly each year and the parasitoid overwinters as a second instar larva within the body of the overwintering host.