Biological Control

Simon Fraser University, Vancouver, British Columbia: 16mm.
"Shows the work being done by Agriculture Canada's research station in Regina, Saskatchewan in the area of biological control - animal or plant pests are reduced in number by use of their natural enemies and diseases instead of chemicals. Their successful work in the control of thistle by release of a certain species of weevil, and the control of nap weed in the interior of British Columbia by a species of gall fly is discussed. Points out the advantages and disadvantages of biological control versus chemical control."