long-tailed dance fly

not listed

not listed

not listed

Long-tailed dance fly is a small, 5 ⁄16″ to ⅜″ long, black, long-legged fly.

The thorax is large and bulbous, making the insect appear hump-backed.

The abdomen is long and tapered. On the male, there is a conspicuous genital capsule under the abdomen. It is not folded forward. The female’s abdomen is longer than the male’s, the attribute that gives the species its common name “long-tailed”.

The wings are black and long, longer than and completely covering the abdomen.

The head is rounded. The neck is long and distinct. The compound eyes are large and bright orange or red. The proboscis is long. The antennae have three segments. The terminal segment has a long, slender style at the tip.

The legs are long, slender, and pale. On the female, the middle and hind legs have a fringe of long, black, bristly hairs.

Total length: 5 ⁄16″ to ⅜″

Deciduous woods near water

May to July

Every evening around sunset, males and females collect in same-sex swarms (leks). Females and fly up and down, the behavior that gives this family its common name “dance-flies”. Females cannot hunt for prey. They receive protein from males as gifts in exchange for copulation. They swallow air, filling and extending their abdomen outward, saucer-like, falsely signaling males that their eggs are nearing maturity. The long hairy legs wrap around the abdomen, making it appear even larger. Males are attracted to females that have largest swollen abdomens and hairiest legs. An individual will break off and join the other swarm to select a mate.

Small insects

Small insects

Sources

24, 29, 30, 82.

Common

Location: Woodbury, MN

Location: Brooklyn Park MN

Location: Woodbury, MN