The Chironomid fauna of a shallow recreational lake was studied from April 1977-April 1978. Benthic larval densities were assessed weekly or biweekly by collecting Ekman dredge (15 x 15 cm) samples; prevalence of adults was studied from their weekly accumulations in New Jersey light traps. Eleven species of midges were collected; Tanytarsus [n. sp. 2 and 3 after Sublette (Darby 19620], Chironomus decorus (Johannsen), and Procladius freemani Sublette, were quantitatively important. Larvae of Tanytarsus spp., were dominant prevailing at 100-2500/0.09 m2 (=1 ft2) and were highest in the spring and summer months when as many as 50 thousand adults/trap/week were collected. The seasonal quantitative composition of adult Tanytarsus spp. and Chironomus spp. generally correlated with their prevailing larval numbers, but Procladius spp. did not follow this pattern. Two applications of the insect growth regulator diflubenzuron (25% WP) at 0.012 ppm during April-August 1977 gave excellent control of the midges for 2-3 weeks after each treatment. In laboratory studies, chlorpyrifos was highly toxic to Tanytarsus spp. and C. decorus, was relatively less toxic to P. freemani. Temephos and fenthion were very active against Tanytarsus spp. but temephos was ineffective against P. freemani. Fenthion showed poor activity against C. decorus and P. freemani; malathion also was only slightly toxic to P. freemani. Some new synthetic pyrethroids, exceptionally toxic to Tanytarsus spp. (LC90 values 0.023-0.058 ppb). were also highly active against C. decorus and P. freemani.