Sequential Sampling in Surveys of Overwintering Larvae of Spruce

A sequential sampling system for classifying infestation levels of overwintering larvae of the spruce budworm, Choristoneura fumiferana, (Clemens), is described. Sequential tables for critical densities ol larvae on balsam fir and red spruce are presented for 70%, 80%, and 00",, confidence intervals. T h e system is based on data collected in Maine and uses a maximum of 6 branches, 3 from fir and 3 from spruce. Simulations illustrating error rates and effort saved using the system are discussed