The efficacy of naphthalene, sulfur, and a commercial combination of these chemicals as a repellent against the plains garter snake (Thamnophis radix) was investigated. Behavioral tests were conducted using 96 recently captured snakes to determine whether significant avoidance results from the presence of these chemicals. Field tests were performed at 24 locations in the snakes\u27 home range and in unfamiliar habitats. In both home ranges and unfamiliar habitats application of potential repellents did not result in significant avoidance behavior. The snakes may be able to sense these volatile chemicals, but the stimuli were unable to alter their behavior. Based on this study, tendency to seek cover, refuge, familiar habitat, or to investig...