A Beneficial Garden Insect
Dolichopodids are small (4-9 mm), slender flies, which are usually brilliantly colored with metallic hues of green, blue, copper, gold, and silver. Some species are gray or black. They are characterized by 2 long wings and long slender legs.
Dolichopodids occur in diverse habitats; larvae are commonly found in moist soil and under tree bark and adults are often abundant near streams, and are found on foliage, tree bark, and flowers of various plants. Both larvae and adults are predaceous on many other insects and small arthropods, including mites, thrips, psocids, aphids, and other insects larvae. The maggot like larvae of the long-legged fly are found in such habitats as soil, rotted vegetation, mud, and under bark. Most are predators or scavengers.
As these are beneficial insects, no control is necessary.
Sources — SCIAPODINAE, MEDETERINAE (INSECTA: DIPTERA) with a Generic Review of the Dolichopodidae