Predators of Larvae of Neodiprion swainei Midd. (Hymenoptera: Tenthredinidae)

Abstract

In 1958, Pilophorus uhleri (Knight) (Hemiptera: Miridae), Vespula vulgaris (L.) and V. rufa consobrina (Sauss.) (Hymenoptera: Vespidae) were recorded for the first time as being not only active predators of Neodiprion swainei larvae, but also vectors of a virus disease affecting this sawfly (Smirnoff, 1959). The latter vespid was considered to be especially important. In the summer of 1959, in the same area (St. David de Falardeau, Lake St. John region, Que.), more insect species were identified, which preyed on the first- and second- instar larvae of N. swainei. Most active were Lasioglossum (Evylaeus) sp. (Hymenoptera: Halictidae) and Crabro sp. (Hymenoptera: Sphecidae), while three species of Vespula were also observed: V. maculata (L.), V. arenaria (Fab.) and V. norwegica norvegicoides (Slad.) (Figs. 1-4). This completes the list of insects which have been observed to prey on swainei larvae. Data were also obtained on the period of greatest activity of each of these predators.