I have some sort of fly/bee destroying my (just formed) grapes
I have a well-established concord grapevine, has produced nice grapes the past 4-5 years. This year I have a LOT of these small fly/bees dislodging the grapes from the stems. I've never seen this before, any advice? (picture of fly/bee on stem attached)
Denver County Colorado
Those are some kind of march fly (Family Bibionidae). The adults feed on nectar. The larvae develop in decaying plant matter and can be common in lawns or other moist sites.
They are harmless to humans and plants.