Long-term sampling of Eucallipterus tiliae (Homoptera : Drepanosiphidae) and associated natural enemies in a northern California site

Introduced Eucallipterus tiliae (L.) populations on Tilia cordata Miller in northern California were sampled from 1981 to 1987. E. tiliae uas more abu ndant in the lower canopy, with a tendency toward higher numbers in the nor theastern sides of trees, but had no consistent pattern regarding inner ver sus outer canopy. Aphid population densities fluctuated irregularly each se ason and were not associated with parasitoid or predator densities. Trioxys spp. (presumed to be predominately T. curvicaudus Mackauer) were the most numerous associated natural enemies; and most abundant on the inner leaves of the lower canopy on the northeastern sides of trees. Both E. tiliae and parasitoids were significantly more abundant on trees with Argentine ants, Linepithema humile (Mayr), present. Trunk banding with a sticky barrier exc luded ants fi om trees in early- and midseason, but bands lost their effect iveness late in the season. An unsuccessful attempt to establish Praon flav inode (Haliday) on E. tiliae is also reported.