Methomyl at seven concentrations, 0.051 to 0.204 kg ai/378.5 l water, was evaluated against eggs of pest and beneficial insects and mites associated with apples. The pest eggs studied were: Laspeyresia pomonella, Panonychus ulmi, Platynota spp., aphids, and Argyrotaenia velutinana. For A. velutinana, five rates of methomyl ranging from 0.013 to 0.204 kg ai/378.5 l water were used. Platynota spp., aphid, and A. velutinana eggs were highly susceptible to the material. P. ulmi eggs were not susceptible. Eggs of beneficial syrphid flies, Aphidoletes aphidimyza, Leptothrips mali, and Stethorus punctum were highly susceptible to methomyl. Eggs of Orius insidiosus were moderately susceptible. Chrysopa spp. eggs appeared to be unaffected by the material. LC₅₀ values for methomyl on eggs of Platynota spp. L. pomonella, O. insidiosus, Chrysopa spp., and S. punctum were generated. LC₅₀ values for P. ulmi eggs were unobtainable. Three rates of methomyl, used as an ovicide, were evaluated in the field for control of the Platynota spp. complex on apples compared to two formulations of FMC 45806, permethrin, and Bacillus thuringiensis. Methomyl provided the best control. Seasonal activity of P. flavedana and P. idaeusalis were monitored in reference to degree-day accumulations. Regression equations for male moth flights and egg deposition of the species are presented. Seasonal activity and prospects for development of a phenology model to predict seasonal activity of the species is discussed. / Master of Science