Severe outbreaks of the ash sawflyTomostethus nigritus F. (Hymenoptera: Tenthredinidae) on ornamental trees in oslo

During spring and summer 1990 observations on the biology of the ash sawfly,Tomostethus nigritus F. were made and control options discussed. The sawfly overwinters as an co- or pronymph in the soil, and pupates in earlys spring. The tlight period lasted for about 3 weeks. The larvae fed on the leaves till June. Injecting the systemic insecticide Carbicron 50 SCW (Dicrotophos) was successful.