• Environment Canada
  Canadian Forestry Service
  

One of the chief concerns when spraying forests to prevent spruce budworm damage is to ensure that organisms other than the budworm are not unduly affected. Because fishing is such an important industry and pastime in the Maritimes, effects on fish and fish-food organisms are hard to tolerate. The main fish-food organisms are aquatic insects, which one expects to be susceptible, to some degree, to insecticides.

B.t. is the common name for Bacillus thuringiensis, a bacterial insecticide that is selective for insects, caterpillars in particular. B.t. is more specific than chemical insecticides and although more costly, a strain called kurstaki is used against spruce budworm in sensitive places. Nobody has been able to detect mortality of aquatic insects during an operational B.t. budworm spray, but the field methods are imprecise.