Midges Flies and Mosquitoes: Diptera - Stalk-eyed Fly (cyrtodiopsis Dalmanni): Species Accounts

Physical characteristics: This species is about the size of a house fly. The compound eyes, or eyes with multiple lenses, are located on the tips of horn-like structures, or stalks, that project from the sides of the head. The distance between each eye on a male is nearly equal to the length of its body. The eye-stalks of the females are much shorter.

Geographic range: This particular stalk-eyed fly is widespread in Southeast Asia.

Habitat: They live on damp, shady forest floors near streams.

Diet: The larvae eat plants, while the adults feed on nectar and other plant juices.

Behavior and reproduction: Males stake out rootlets on the ground and compete with one another for females. Males face one another and Stalk-eyed flies are observed by scientists who study courtship behavior. Males stake out rootlets on the ground and compete with one another for females. Males face one another and wrestle each other with their front legs. (Illustration by Jonathan Higgins. Reproduced by permission.) wrestle each other with their front legs. Eventually the male with the shortest eye-stalks backs down. Females prefer large-bodied males with long eye-stalks as mates. They are usually found in small groups. A single male will mate with up to twenty females in just thirty minutes.

Upon emerging from the pupa, stalk-eyed flies pump body fluids into both their wings and eye-stalks for up to fifteen minutes until they expand to their full lengths.

Stalk-eyed flies and people: These fascinating animals are observed by scientists who study courtship behavior.

Conservation status: This species is not considered endangered or threatened. ∎