Introduced to the technical aspects of forestry aerial spraying in the mid-1970's, we were immediately impressed by the complexity of the process of delivering pesticide to foliage. At that time, there was a vigorous public debate in New Brunswick about the ecological and public h~alth impacts of the annual spray program for the control of defoliation of spruce and fir trees by the spruce budworm. The forest industry is important to the province and changes to the established procedures of budworm control could have major economic implications. A rational debate required reliable information...