Douglas Fir Tussock Moth Egg Hatch and Larval Development in Relation to Phenology of Grand Fir and Douglas-Fir in Northeastern Oregon

摘要

Bud burst, shoot elongation, egg hatch, and larval development were studied on six areas in a 1973 infestation of the Douglas Fir Tussock Moth in the Blue Mountains. Bud burst and egg hatch were found to be closely related to accumulated degree-days, and peak egg hatch occurred after all buds had burst and shoots were 50 percent or more elongated. Larval development then closely followed shoot elongation. This synchrony of host and insect phenology provides an easily observed field event for monitoring Douglas fir tussock moth development.