The management of insect epidemics in large tracts of forest is difficult given the climatic conditions encountered, the topography of the forested land, the nature of the forest, the types of chemical and/or biological insecticides registered for use, and the technologies available for insecticide application. Since 1952, the province of New Brunswick, Canada, has been heavily involved in attempting to control an epidemic of the eastern spruce budworm (Choristoneura fumiferana. Clemens) that has ravaged the coniferous softwoods of eastern Canada and the United States. Of the available options, the provincial government chose to develop an aerial spraying program, eventually selecting two chemical insecticides (fenitrothion and aminocarb) and one biological control agent (Bacillus thuringiensis). Concerns about possible impacts on human health led to extensive studies of the toxicology of these insecticides, the technology of aerial spraying, the development of less hazardous formulations, and the quantitation of off-target drift of aerosolized insecticides. These studies culminated in improvements in pesticide application and the establishment of regulations on safety or buffer zones around human habitation for certain types of aircraft applying different formulations of the insecticides.