• Carrow, J.R.
  Pacific Forest Research Centre
  
• Buckner, C.H.
  Chemical Control Research Institute
  
• McLeod, B.B.
  Chemical Control Research Institute
  
• Langer, O.E.
  Fisheries and Marine Service
  
• Taylor, R.
  Fisheries Operations Pacific Region
  
• Wan, M.T.K.
  Environmental Protection Service
  
• Richmond, H.A.
  Council of Forest Industries of British Columbia
  

In June 1973, an aerial spray project was conducted by the Council of Forest Industries of British Columbia and the Province of British Columbia to protect 29,000 acres of hemlock forest on northern Vancouver Island from additional defoliation by an outbreak of blackheaded budworm, Acleris gloverana (Wlshm.). Environment Canada provided entomological and technical advice and assessed the effectiveness of the operation, as well as its effects on non-target organisms. The formulation used was 2 oz fenitrothion in 20 oz water per acre applied twice at a four-day interval. Spraying resulted in 80% control of blackheaded budworm in young stands (up to 40 ft) and 46% control in older stands (over 100 ft). The foliage protection value of the spray was difficult to determine accurately because the larval population collapsed prior to heavy feeding; however, spraying resulted in a 14% improvement in the crown condition of young stands. The budworm population experienced a sudden collapse, due to natural causes, shortly after spraying and the evidence suggests that it was associated with 11 days of continuous rain and cool temperatures during early July. Spray assessment indicated a ver¥ low ground level deposit and spray drift onto the leave strips surrounding fish-bearing waters; trace amounts of spray were also detected up to six miles from the spray boundary.

Monitoring of the effects of the operations on non-target organisms revealed that populations of juvenile salmon, songbirds and small mammals suffered no immediate ill effects. However, there was considerable mortality of several families of aquatic and terrestrial insects.