The Yellow-spotted Sapeater (Brachyopa vacua) is a small, brown Nearctic species. The thorax is gray with purplish overtones. Segment two of the abdomen is almost entirely yellow, while segment three has small spots of yellow on the anterior corners. Goggle-eyed, slightly irregular in shape, the eyes sweep forward along the produced face. Most specimens have been found at elm tree wounds. The flies are observed hovering in front of the wound, perched adjacent to the flow of sap, or ovipositing directly into the flowing sap. The larvae feed on the sap and live in the wounds.Field notes: The bi-colored abdomen visible through the folded wings, at first glance, creates the illusion that the wings are banded.
Flight Dates: June
Flowers: Adults are most commonly observed at flowing wounds on elm trees, but they have occasionally been observed at flowers, including Goats Beard, Dogwood, and Cow Parsnip.
Similar species: Most similar to other Brachyopa species. Also could be confused with Hammerschmidtia rufa.
Field Notes: The bi-colored abdomen visible through the folded wings, at first glance, creates the illusion that the wings are banded.