"Diamesa larvae are usually found in cool running water."(1)
Season
Adults typically fly in winter.
Food
Adults probably do not feed, if only for lack of suitable food sources.
Print References
Hansen, D. C. and E. F. Cook. 1977. The systematics and morphology of the nearctic species of Diamesa Meigen, 1835 (Diptera: Chironomidae). Memoirs of the American Entomological Society 30:1-203 (BHL)