In a recent post (Butterflies Galore), I showed a picture that I said showed native bees with a skipper butterfly. But I was curious about the bees — I’d never seen anything like them before. I couldn’t find anything on the internet, so I emailed the University of Colorado Museum of Natural History. According to the folks there, they aren’t bees, they are a type of tachinid fly! (Adejeania vexatrix)
Turns out that adult Tachinid flies feed on flower nectar, which means that they are pollinators, especially at higher elevations, where bees don’t live. (Alpine flowers on Mt. Evans) On the other hand, their larvae feed on other insects, including some that are harmful to crops. They are found from the tropics to the arctic, and can look like houseflies or be more unusual, like these.