A few weeks ago I found a number of these small long-legged flies (Diptera: Dolichopodidae: possibly Condylostylus). They were buzzing around the edge of a woods along the River Raisin in southeast Michigan, and they kept stopping to rest on foliage long enough to photograph them. They’re often found near swamps and streams similar to the area where I found these individuals (Triplehorn and Johnson 2005). Adults and the larvae of many species are predaceous on smaller insects, and some larvae feed on pestiferous bark beetles (Triplehorn and Johnson 2005).
Most males in this family have very large genitalia that they keep tucked under their abdomens. Females like the one shown here have pointed abdomens (Triplehorn and Johnson 2005). Regardless of gender, most of these flies are metallic blue, green, or copper and have relatively long legs. Some other flies exhibit these characteristics as well, and is often the case it’s necessary to examine the wing venation for positive identification.
Triplehorn, C.A. and N.F. Johnson. 2005. Borror and DeLong’s Introduction to the Study of Insects. Seventh Edition. Thomson Brooks/Cole, Belmont, CA.