dance fly

Empis is a large genus of small dance flies. Numbers vary, but according to Catalogue of Life there are 976 Empis species worldwide. Empis clausa is a small dance fly. It occurs in the United States from the Upper Midwest to the southern Great Plains. Little is written about this or any other Empis species,

Adults are about ⅛″ (4 mm) in length. The body is long and slender but relatively robust.

The head is small and more or less spherical. The antennae have three segments. The third segment is rounded, it is not ringed, and it has a long terminal style. The compound eyes are large and dull orange. The mouthparts are extended into a long, rigid proboscis.

There is a distinct, narrowed neck, visible from the side, connecting the head to the thorax. It allows for considerable head mobility.

The thorax is black, large, and bulbous, making the fly appear hump backed.

The legs are long and slender. On the female, the middle and hind legs have a feather-like fringe of long black hairs.

The wings are clear with dark veins and dark banding along the cross veins. The radial sector vein (Rs) has only two branches (R₄₊₅ is not forked). The radio-medial (r-m) cross vein is beyond the basal quarter of the wing. The anal cell is shorter than the second basal cell.

The abdomen is long, tapered, and mostly black. There is a variable amount of orange on the ventral (underside) and sides of the first two abdominal segments, from slightly tinged to almost entirely orange. On the male, there is a conspicuous genital capsule under the abdomen. It is not folded forward.

Total length: ⅛″ (4 mm)

Adults form mating swarms. The male will capture an insect and offer it as a gift to a potential mate.

Sources

24, 27, 29, 30, 82, 83.

dance fly of some kind, maybe Empis clausa.
CenTex66

Mike Poeppe
7/6/2025

Location: near Houston, MN