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.
The Back-spotted Falsehorn (Temnostoma excentrica) is a large, yellow-and-black, Nearctic flower fly. A convincing Yellowjacket Wasp (Vespinae) mimic. In addition to being a visual mimic, this fly (and the other Falsehorns) lift and wave their black forefeet in front of their heads, imitating the antennae of wasps. Markings on thorax are whitish-gray in color. Paired yellow bands enclose a pair of black, rectangular spots on the 4th and 5th abdomen segments (open on segments 2 and 3). In the north, the abdominal markings can be white instead of yellow, mimicking the Bald-faced Hornet (Dolichovespula maculata).
Larvae found in decaying wood
Flight season: June
Similar species: Temnostoma alternans, Spilomyia alcimus, Spilomyia fusca, Somula decora, and Sphecomyia vittata, which are all yellowjacket mimics.
The Long-nosed Swamp Fly (Eurimyia stipata) is a small, gray, yellow, and black, Holarctic species. Unlike most other Syrphidae, female and male eyes are separated. Males have thinner abdomens and are the more colorful. The larvae have long tails and are found in wet areas with decaying vegetation at the edge of ponds and other wetlands.
The taxonomy of this species is a little messy. In Europe it’s Anasimyia lineatus. Here it has been known as Lejops lineatus or Lejops (Eurimyia) lineatus or Eurimyia lineatus, and currently Eurimyia stipata. The common name, Long-nosed Swamp Fly, simplifies the problem.