The goal of this research was to improve the understanding of the dynamics of male gypsy moth-pheromone trap interactions and the ecological factors that influence moth capture in pheromone traps. Defoliation, the most obvious expression of high density gypsy moth populations, may have a significant influence on gypsy moth population dynamics. This research focused on the use of defoliation and defoliation related processes to study moth capture in pheromone traps. Male moth wing length was found to decrease substantially only when defoliation exceeded a threshold level of ca. 40%, resulting in moths with either large or small wings. Moth wing length, determined from moths captured in intensively monitored traps, was found to accurately estimate whether or not defoliation exceeded ca. 40% in the vicinity of the trap. However, for traps serviced less intensively, male wing length provided a poor estimate of defoliation. Larval development (using degree-days as a physiological measure of time) in sixteen plots was not altered as a result of varying levels of defoliation, but pupal phenology was significantly influenced by the level of defoliation . Despite distinct differences in pupal phenology, there were no differences in male moth capture over time in pheromone traps attributable to defoliation. A broad relationship between the number of moths captured and egg mass density was developed. The spatial and temporal characteristics of gypsy moth populations were examined using a combination of field studies and defoliation maps. This information, in conjunction with data on wing length and the relationship between moths per trap and egg mass density, was used to develop an algorithm to interpret moth capture in pheromone traps to monitor gypsy moth populations. / Ph. D.