Olfactory responses of lesser cornstalk borer,Elasmopalpus lignosellus(Zeller), larvae to conspecific individuals and peanut plant parts were determined in olfactometer studies. Larvae were not attractive to conspecifics. Young peanut pods infested by two larvae had the same attractiveness as intact pods. Peanut roots, pegs, and pods attracted significantly more larvae, although there were some differences in attraction between lesser cornstalk borer instars. Roots and young pods attracted more small and large larvae. More medium larvae were attracted to pegs and roots. Olfactory responses of larvae to peanut roots were eliminated after antennae were treated with N-methylmaleimide (1 mg/ml in 100% ethanol). There were no differences between the responses of untreated larvae and those with only the palpi blocked. Larval olfactory response to peanut plant volatiles therefore depends primarily on the antennae.