To decide about controlling leafminers, Phyllonorycter spp., with insecticides, most researchers, extension agents, and private consultants monitor populations by measuring the density of mines in apple, Malus domestica Borkhausen, leaves. Egg density, especially for the first generation, is measured less frequently. In some orchards infested by P. blancardella (F.), pheromone traps are used for determining leafminer activity. Especially in New England and eastern New York, adult leafminers are monitored with visual traps. Current action thresholds for leafminers are based on the effect of feeding injury on tree physiology, on the potential increase from one generation to the next, and, in some instances, on the level of parasitism. Currently, most growers apply pyrethroid or carbamate insecticides to control adult leafminers of the first flight or larvae of the first generation. Parasitoids sometimes limit leafminer outbreaks; therefore, their conservation by improving the selection of insecticides and the timing of applications may have potential for managing leafminers. Mating disruption, leaf chopping, or urea sprays are non-conventional strategies that may be used in future management. Leafminers management could be improved in future research were to focus on parasitoid phenology, ways to reduce or better time sprays to conserve beneficials, reevaluation of economic thresholds (especially in the absence of daminozide), mating disruption, effects of leaf chopping and urea sprays on leafminers and their parasitoids, and susceptibility of different apple cultivars to leafminer injury.