In recent years, adult Chironomidae (particularly Chironomus yoshimatsui and Tokunagayusurika akamushi) emerging from polluted natural and man-made aquatic habitats in urban areas of Japan have become intolerable because they pose severe nuisance and economic problems. Several organophosphorus (OP) insecticides and insect growth regulators (IGRs) including methoprene and diflubenzuron were tested in the laboratory against C. yoshimatsui and several other midge species. The OP insecticides were effective against the midge larvae except for Procladius sp. Both IGRs were highly effective against C. yoshimatsui at concentrations less than 0.001 ppm; diflubenzuron showed superior activity over methoprene. In field studies, temophos has been successfully used at rates ranging from 0.1 to 2 ppm against C. yoshimatsui and several other species in a variety of habitats. Diflubenzuron at 1 ppm rate of treatment provided excellent control of C. yoshimatsui in polluted rivers while methoprene at the same rate was less effective. Frequent field use of temephos and fenthion has led to increased tolerance of these insecticides (particularly the latter) by C. yoshimatsui.