Black-spotted Falsehorn

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.

Flowers: Elderberry (Sambucus sp.)

Temnostoma excentrica – Lake Metigoshe State Park, ND – June 12, 2016

Long-nosed Swamp Fly

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.

Flight season: May – July

Flowers: Sweetflag Iris, Spiderwort, Creeping Thistle

Similar species: Lejops bilinearis and Parhelophilus sp.