Pissodes strobi and P. nemorensis are weevils (Coleoptera, Curculionidae) that infest pines (Pinus spp.) and spruces (Picea spp.). Previous studies indicate that they are able to hybridize. In the spring, breeding site specificity maintains reproductive isolation, but in the late summer, both species occupy lateral branches of host trees. Aggregation pheromones for P. nemorensis have been identified but the mechanism for late summer isolation is unknown. Cuticular hydrocarbons have been shown to play a role in the chemical recognition of species, sex, kin, and caste in many groups of insects. The large number of possible compounds and the even larger numbers of possible combinations creates potential for much information to be encoded. Cuticular hydrocarbon samples from P. strobi were collected from an infestation in a white pine stand in Pompey, NY. The cuticular hydrocarbon samples were analyzed by coupled gas chromatography-mass spectrometry. Statistical analysis of the cuticular hydrocarbon profiles revealed a shift of the cuticular hydrocarbon profile between spring and summer males while the profile of the females remained constant between the two seasons. This shift in cuticular hydrocarbon profile may be indicative of a seasonal change that prevents P. strobi and P. nemorensis from interbreeding in the summer when the two species share the same habitat
