Sampling Western Spruce Budworm by Counting Larvae on Lower Crown Branches

摘要

A technique is described for sampling spruce budworm larvae after bud flush by nondestructively beating branches in the lower crown. Sample data were collected from 32 plots representing a wide range of budworm densities. Statistical analyses indicated that larvae were less aggregated in the lower crown than at the same density in the middle crown. In an independent sample of 12 plots, estimates of larval density in the middle crown were 2.5 times higher than but strongly correlated with density in the lower crown. Sampling in the lower crown is quick and efficient and especially recommended for the annual monitoring of larvae or for estimating densities before spraying in control programs.