The seasonal occurrcnce of life-history stages of Bucculatrix ainsliella Murtfeldt (Lepidoptera: Lyonetiidae), and the level or attaek by parasitoids on larvae and pupae, were determined for a population occurring on red oak trees (Quercus rubra L.) in an urban area of Burnaby, BC. B. ainsliella completed two generations in Burnaby in 1997, and a substantial increase in population density occurred between the first and second generations. Pupal parasitism reached high levels (>40% parasitism) during the first generation in this population, but larval parasitism occurred at a very low level. Dispersal of large numbers of second-generation larvae on silken threads, and subsequent pupation on parked vehicles on residential streets, cause much of the pest impact of this "nuisance" inscct. Attack by pupal parasitoids in the first generation probably reduccs the pest impact of these second-generation larvae.
