Crawlies with Cri: feather-legged fly

(Photo by Christy Solo, Illinois Valley News)

Trichopoda pennipes feather-legged fly

This week’s crawly will help you squash a pesty problem. Meet the Trichopoda pennipes feather-legged fly.
Trichos (as we’ll call them) are parasitoids of several families of true bugs (Hemiptera).
Quick refresher: “Parasitoid” means that the young of the tricos eat their “host”; in the case of tricos it’s adult bugs which are on the menu.
Tricos’ main and favorite host is the squash bug (Anasa tristis). Don’t let the name fool you: While squash bugs do prefer – and thrive – by eating squash, they also eat watermelon, cucumber and cantaloupe. Having them around can put a big damper on your summer and fall home garden harvest.
The bad news is we do have squash bugs in Oregon. The good news is we don’t have many and only 10% of the recorded sightings are in Jackson County.
The excellent news is, trico flies – which we have in abundance – will wipe out 80% of the adult population of squash bugs.
Do not swat these flies!
But wait! There’s more! Tricos also parasitize other area bugs which may or may not be particularly pesty. If squash bugs aren’t available female tricos will lay their eggs on leaf-footed bugs, bordered plant bugs, jewel bugs and stink bugs.
Wherever tricos are, they’ll be cutting down the population of potential pests.
Adult tricos feed on nectar so they double down on their beneficial qualities by also being pollinators. While their feathery hind legs aren’t meant for gathering pollen specifically, pollen will adhere to them and spread.
If you want to attract tricos to your yard, plant some chokecherry trees (they like the extrafloral nectaries) and some flowers in the carrot, dill, parsley and/or yarrow families.
With their bold black and orange coloring, tricos are easy to spot and will be on the wing throughout the summer months.
Speaking of spots and their coloration, why do our pictured tricors have different color patterns?
Males have brown across the tops of their wings and a black band near the rear of their abdomens, but the very tail of their abdomens will always be orange.
Females have solid black wings, and the ends of their abs are likewise solid black.
Trico ladies also have a nifty way of finding adult bugs for their parasitoid purposes. True bugs will leave a pheromone trail in their wake to both define their territory and attract mates.
While tricos are very much not what the bugs are hoping to attract with their pheromone trails, likely as not tricos are what they will attract. Tricos developed the ability to smell bug pheromones, so it’s quite easy for female tricos to track down a host for their young.
Females produce an adhesive and use that to glue an individual egg to an unwitting bug. When the young trico hatches, it chows down on the adult bug, then morphs to a cocoon-like form before hatching into a winged adult.
Fun fact: Adult tricos vary in size from one-third to one-half of an inch. Their adult size depends on the size of their host bug. The bigger the bug, the bigger the adult trico will be. Gives a whole new meaning to “you are what you eat.”