• Titus, F. A
  Forest Insect and Disease Survey
  

The egg, larval and pupal stages of spruce budworm are attacked by a series of parasites. At M.F.R.C. we have assessed the levels of parasitism in the larval and pupal stages throughout the season since 1970. Because of the variation in phenological progress between localities from year to year, the use of degree-day accumulations over base 42°F was chosen as the guide to sampling time rather than calendar days. Where this guide is unreliable or impractical, sampling timing is based on observations of budworm development in the area to be surveyed, but that alternative is time-consuming and requires local knowledge.