Both Petrova albicapitana (Busck) and P. metallica (Busck) attack Pinus contorta Dougl. in Alberta. The similarity of their larvae and of the pitch-blister nodules that they construct make it difficult to identify the 2 species in the field; however, they can be separated on the basis of their feeding damage. The abundance of males caught in pheromone traps indicates that P. metallica was more common than P. albicapitana in 1981–1984, and more widely distributed than previously recorded in Alberta. The examination of the feeding damage and the pheromone trapping of males indicate P. metallica occur only in stands of P. contorta in Alberta. Petrova albicapitana, however, was collected in stands of P. contorta, P. banksiana Lamb., and a mixture of P. contorta and P. banksiana. The 2 species differed in seasonal occurrence and abundance at different elevations.