Notes on the larval biology of Xestia borealis (Lepidoptera : Noctuidae)

Observations on a larva of Xestia borealis found in nature are presented. O ur findings support the view that the species has a two-year life cycle wit h two obligatory winter diapauses. Like Xestia sincera, X. borealis seems t o prefer buds and fresh shoots of spruce in its diet. Both species overwint er for the first time as large III-IV instar larvae, after overwintering ra pidly complete their larval development, and subsequently fall into a long summer diapause. We also discuss some features of larval biology of other b oreal Xestia species with a two-year life cycle.