Dispersal Losses of Early-Instar Spruce Budworm (Lepidoptera: Tortricidae) 1 Larvae in Strip Clearcut and Dense Spruce-Fir Forests of Maine 2

Abstract

Strip clearcutting contributed to dispersal losses of early-instar larvae of the spruce budworm. Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae). Significantly more L1 larvae were trapped in uncut residual strips of strip clearcuts than in dense stands. Significantly more L2 larvae were trapped in cut strips than in residual strips or in dense stands. Consistently more L2 larvae were caught than L1 larvae. Mean percentages of L1 + L2 larvae trapped represented small fractions (1.4−4.0%) of initial egg populations. Proportionately more larvae were trapped in strip clearcuts (uncut residuals + Cut strips) than in dense stands. Estimated combined losses (L1 + L2) were 1.4 million larvae per ha for dense stands and 2.9 million larvae per ha for strip clearcuts.