In a southern California reservoir, benthic larval density of chironomid midges was assessed 10 times between Aug. 1974 and July 1975, at>1 m, 3–4 m, and 6–8 m water depths. Larvae belonging to 9 midge genera were taken.Tanytarsusspp.,Chironomusspp., andProcladiusspp. were predominant, forming more than 85% of the total chironomid larvae recovered on any sampling occasion from the entire basin. The monthly qualitative composition of midge fauna differed slightly between the 3 depth levels, but the quantitative composition changed markedly from one level to the next. Midge density was consistently higher in the>1 m deep areas than in the 3–4 m and the 6–8 m deep levels.Tanytarsusspp. were predominant at the>1 m depths.Chironomusspp. andProcladiusspp. were more prevalent in the other 2 deeper regions.