Wikipedia
Nemestrinidae
Nemestrinidae, or tangle-veined flies is a family of flies in the superfamily Nemestrinoidea, closely related to Acroceridae. The family is small but distributed worldwide, with about 300 species in 34 genera. Larvae are endoparasitoids of either grasshoppers (Trichopsideinae) or scarab beetles (Hirmoneurinae). Some are considered important in the control of grasshopper populations. Adults are often observed on flowers.