• Trial, Henry Jr.
  Maine Forest Service
  

The spruce budworm (Choristoneura fumiferana) is by far the most destructive forest insect affecting the spruce-fir type in Maine and eastern Canada. Spruce budworm outbreaks are generally described as cyclic in nature with a 30 to 70 year endemic period followed by an approximately 10 year period epidemic status. Outbreak periods in this century have been recorded for the period 1909 to 1920, a variable outbreak status existed from the mid 1940s through the early 1960s, and a major outbreak which began in the late 1960s lasted through to the early 1980s. This paper employs a cartographic display to illustrate the progression of the spruce budworm outbreak through the 1970s. Features chosen to portray the outbreak are: the area of moderate to severe defoliation, the area treated with insecticide, and the area of host tree mortality.