From 1985 to 1989, the susceptibility of the 9 major culicine mosquito species in Maryland to the larvicide temephos or the adulticide malathion was studied. The susceptibility of Culex spp. to temephos has declined in most areas of Maryland since 1967; however, only one strain of Culex pipiens was found to be temephos resistant in this study. Aedes sollicitans, Ae. albopictus and Ae. taeniorhynchus were temephos susceptible. All mosquitoes tested in the adult stage were susceptible to malathion.