The first time I saw one of these flashy orange flies, I thought it looked like a cowboy with bow-legged back legs and fringed boots. I wasn’t that far off. Its scientific genus is Trichopoda, which means “hair-foot.” Its common name is Feather-Legged Fly.
Experts say the fringes make the flies look like bees, imitating the pollen-attracting hairs on their back legs. That, and the bright orange color may be a warning signal to some predators. This fly holds its wings straight out or even a bit forward, Superman-like, and the wings are partially transparent.
Female Trichopoda flies, like the one shown here, have black at the tip of their abdomens, whereas males are completely yellow/orange.
Feather-Legged Flies are in the Tachinid family, all of which are parasites of other insects. Trichopoda flies target stink bugs, squash bugs, and leaf-footed bugs. For this reason, they’ve been brought to places like pumpkin farms to save the day. Interestingly, the pungent pheromone that stink bugs send out, which attracts their mates but repels bird predators, is a lure for Feather-Legged Flies. They zone in on the male bugs who emit it, and so more males than females are parasitized, at least on certain green stink bugs in the south, where the behavior was recorded.
If you don’t want to read the grisly details of the pupal Trichopoda, skip this paragraph. Females lay eggs on adult and larval bugs. The larvae that develop there tunnel inside the bugs. They don’t kill the bug, but eat its non-essential parts first. Squash bugs are fairly large at about 2/3rds of an inch, and sources say the Feather-Legged Fly grubs fill up nearly the entire exoskeleton of a squash bug before they break out of the cozy live-in pantry and tunnel underground to metamorphose into a fly. That last bit, the “breaking out” is what finally kills the bug!
The adults are about the size of a house fly and eat nectar, not bugs. You can find them posing like little orange cowboys on late-blooming flowers at Mount Pisgah this time of year.
Stay curious!
See more of Karen’s work here.
Sources:
Wisconsin Extension, for attraction to stink bug stink: https://hort.extension.wisc.edu/articles/trichopoda-pennipes-parasitoid-of-squash-bug/. Accessed 10/5/21.
Good general information via Wikipedia: https://en.wikipedia.org/wiki/Trichopoda_pennipes. Accessed 10/5/21.
