Kathy got into her compost bins and “moved a bit of bottom dirt from the older into the new, gave it a spin, opened it again and suddenly had dozens of bumble bees crawling around on the compost.” Flies in this genus are convincing bumble bee mimics and sport very large hind femora (the third segment in the leg of an insect, counting from the body). How to tell the difference between a bumble bee and a fly? Bumble bees have wider abdomens, four wings, longer antennae, and eyes on the sides, while flies have two wings, short antennae, and “fly eyes”: large, often forward facing, sometimes touching on top of head.
Larvae are deposit filter-feeders in water-filled tree holes (say that three times fast!) and the adults visit flowers. These flies are found around woodland and wood edges and range across eastern North America. Kathy’s photo “represents a new state record for BugGuide on the western end of its distribution.”
Size: 11-17 mm
Photo by: Kathy Mackey on 5/30/22 in Missoula, MT