• Raisch, Robert D.
  

The spruce budworm is an insect indigenous to North America and one that has periodically caused extensive tree morality in the coniferous forests of Canada and the United States. Outbreaks of the spruce budworm have been traced back to 1704, but they probably occurred for centuries before that. The budworm is an integral component of the fir-spruce forests of Maine. The forests regenerate after budworm outbreaks. Fir and spruce take 50 to 60 years to reach merchantable size and it's at this age that stands are most vulnerable to attack. The budworm then, is man's competitor for the fir and spruce trees.