These photos are of a Deer Fly in the genus Chrysops. We believe it is the species Chrysops mitis. On different websites, we saw the common name listed for this species as “Benign Deer Fly” (on Montana Field Guides) and “Biting Deer Fly (on Pinterest). Sounds a bit confusing if you ask us. However, our photo submitter and hand model (Sue) can certainly state that this fly is far from “benign”. Sue wrote that, “it would not stop biting us. The photos were accompanied by screaming as my husband was fumbling with the phone to snap a pic and I was in much pain! Now I have two small itchy bites where he feasted.”
According to the Kaufman Field Guide to Insects of North America, “Females of most species [of deer and horse flies] are blood feeders, using knifelike mouthparts to slice and dice, then slurping up the flow with a spongelike proboscis.” If you resort to smacking the offending fly after being bitten, take comfort in the fact that you also removed the next generation for that individual. Only the females bite; males sip flower nectar.
Thanks, Sue, for taking one for the team to allow for this photo!
Size: Less than .5 inches (un-squished)
Photos by: Dave Lowery on 7/17/22 in Missoula MT