• Leonard, David E.
  University of Maine
  
• Simmons, Gary A.
  University of Maine
  

Parasitic insects are among the naturally occurring agents that kill spruce budworm. Generally, parasitic insects cannot bring about the collapse of a spruce budworm outbreak, but they can hasten a collapse once started or help prevent a rapid population explosion if necessary conditions exist.

Current strategies are to spray spruce budworm infested areas when the insect population will cause tree mortality. Extensive areas are often sprayed. Within these large spray blocks are included areas of pure spruce and fir plus areas of hardwoods mixed with the spruce-fir type. These areas containing hardwoods often have in them insects similar to spruce budworm but much less damaging, serving as a "reservoir" for parasitic insects capable of attacking spruce budworm.

The rationale for this project was to see if areas of spruce-fir containing mixtures of various species of hardwoods would also harbor (1) lower populations of budworm, and (2) greater percentages of parasites. If this is the case, perhaps these areas may be excluded from spruce budworm control projects because natural agents are affecting sufficient control. If such areas are excluded, the cost of suppression may be substantially reduced.