A study to determine the degree of similarity and/or diversity among eight of the 15 described species of Conophthorus is reported. Cuticular hydrocarbons were evaluated for C. conicolens, C. ponderosae, C. cembroides, C. edulis, C. radiatae, C. coniperda, C. resinosae, and C. banksianae. Seventy-eight individual and isomeric mixtures of hydrocarbons were identified by gas chromatography-mass spectrometry, including n-alkanes, alkenes, alkadienes, 2- or 4-methylalkanes, 3-methylalkanes, and single-component and isomeric mixtures of internally branched mono-, di-, and trimethylalkanes. Differences in alkenes and mono-, di-, and trimethylalkanes can be used easily to separate the eight species. Conophthorus conicolens and C. ponderosae contain the most complex blends. Hydrocarbon patterns in three geographically separated populations of C. ponderosae, each from a different host, are qualitatively identical with the exception of a homologous series of 3,7-dimethylalkanes from adults collected from Pinus lambertiana cones. The latter could comprise a sibling species. Hydrocarbon mixtures of two eastern species, C. resinosae and C. banksianae, are qualitatively identical, supporting the suspicion that C. banksianae may not be a valid species. Closely related C. cembroides and C. edulis have similar combinations of hydrocarbons except for a unique and abundant alkene (C27:1) in C. edulis and two dimethyhexacosanes in C. cembriodes. © 1990 Plenum Publishing Corporation.