Laboratory studies were conducted to determine the toxicity of a number of insecticides to adults of the carrot weevil, Listronotus oregonensis (LeConte). Initial screening tests indicated that, in general, carrot weevil adults were quite tolerant to insecticides. However, several materials showed sufficient activity as direct contact, residual contact-stomach, and soil insecticides to warrant testing under field conditions. These included Zinophos® (O,O-diethyl 0–2 pyrazinyl phosphorothioate), WL 24073 [O-(2-chloro-l-(2,5-dichlorophenyl)vinyl) O-methyl ethylphosphonothioate], WL 25735 [O-(2-chloro-1-(2,5-dichlorophenyl) vinyl) O-methyl methylphosphonothioate], Pirimiphos-methyl® (O-[2-(diethylamino)-6-methyl-4-pyrimidinyl] O,O-dimethyl phosphorothioate), tetrachlorvinphos, and parathion. Although less active, Biothion® [(O,O′-thiodi-p-phenylene) O,O,O′,O′-tetramethyl phosphorothioate], carbofuran, and chlorpyrifos were also considered sufficiently effective to warrant further study.