• Cameron, D.G.
  Forest Research Laboratory, Department of Forestry and Rural Development, Fredericton, New Brunswick, Canada
  
• McDougall, G.A.
  Forest Research Laboratory, Department of Forestry and Rural Development, Fredericton, New Brunswick, Canada
  
• Bennet, C. W.
  Forest Research Laboratory, Department of Forestry and Rural Development, Fredericton, New Brunswick, Canada
  

Ability predict insect development and the phonological development of the host tree is important in determining sampling dates for population studies and in timing the application of chemicals or control operations. heat unit accumulation, although computed in different ways by different investigators (Arnold 1960), have sometimes been used successfully to predict phenological events. This note gives the number of heat units used to access larval development of the spruce budworm, Choristoneura Fumiferana (Clemens), and to set sampling and spraying dates in New Brunswick. the relationship between the shoot growth of the major host, balsam fir, Abies Balsamea (L.) Mill., and accumulated heat units also is tabulated.