DEVELOPMENT OF METHODS FOR SAMPLING THE ORIENTAL FRUIT MOTH, GRAPHOLITHA MOLESTA (LEPIDOPTERA: TORTRICIDAE), IN AN ONTARIO PEACH ORCHARD

Abstract

Methods of sampling to measure factors affecting fluctuations of a population of the Oriental fruit moth, Grapholitha molesta (Busck), on the Niagara Peninsula of Ontario were investigated from 1963 to 1967 in peach orchards in which no insecticides were used during the study. In most years females tended to be distributed evenly throughout the orchard and even at low fruit moth densities the trees were relatively evenly infested. Several sampling methods gave estimates of the numbers of larvae overwintering in the orchard only within wide limits but indicated that the numbers were probably small in all years. Eggs could be sampled but it was not practicable at the low densities of the moth in this study. No satisfactory method of sampling summer cocoons or adults was found. Destructive sampling of the larvae, in which they were removed from the trees and reared to maturity on green apples, gave the most precise estimates of numbers in each generation. The method also gave a measure of mortality, parasitism, and times and duration of each generation.