From Wikipedia:
Asteiidae is a small but widespread family of acalyptrate flies or Diptera. About 130 species in 10 genera have been described world-wide. They are rarely collected.
Adult asteiids are small (1-3 milimeter), thin-bodied, delicate flies. The wings are relatively long and transparent.
Biology: Adults have been collected at windows and tree wounds. Larval biologies are unknown, but adults have been reared from fungi, stalks of Cannabis sativa, flower buds, and dried reed stems. Sabrosky (1987) suggested that the larvae may be scavengers in the frass of other insects.

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