The neem tree,Azadirachta indicais the source of azadirachtin and other compounds with potent insecticidal, feeding deterrent, and insect growth regulator activity. This study investigated the effects of a commercial insecticide formulation (Margosan‐O) containing 0.3% azadirachtin and 14% neem oil on orientation, tunnelling, and feeding behaviour of the Formosan subterranean termite,Coptotermes formosanus.In short‐term orientation assays, termite workers did not avoid papers treated with a 1000 ppm solution of azadirachtin. Termite workers also readily penetrated sand containing 20, 100, or 500 ppm azadirachtin, although significant mortality occurred in the 100 ppm treatment. However, subsequent observations indicated that termites avoided long‐term contact with the treated sand. In two multiple‐choice feeding assays, C.formosanusworkers fed significantly less on papers containing azadirachtin concentrations >100 ppm. Azadirachtin, and possibly other neem oil components, thus show some toxicity, long‐term repellency, and feeding deterrent activity towardsC. formosanusalthough the threshold for antifeedant effects is relatively high in comparison to thresholds for other insect species.