• Flexner, J. Lindsey
  
• Basset, John R.
  
• Montgomery, Bruce A.
  
• Simmons, Gary A.
  
• Witter, John A.
  

The spruce budworm periodically causes severe damage in coniferous forests in the Lake States, particularly in Michigan's Upper Peninsula and in northern Wisconsin and Minnesota. The insect feeds primarily on balsam fir and white spruce (Fig. l). How ever, when budworms are numerous, they will feed on nearby secondary host species such as black spruce, eastern hemlock, eastern larch, blue spruce, and eastern white pine. Mature and over mature trees are most likely to be damaged, but trees of all ages may suffer injury or mortality during an outbreak.