Reports of cutworms (in populations high enough to warrant spraying or to destroy significant acreages where they were missed) have been reported in isolated fields right across western Canada. Cutworm damage often appears as bare patches showing up across the field. Plants in these areas will be wilted or dead and have been chewed off below the soil surface. A sample received at Saskatchewan Ministry of Agriculture was identified as the Bronzed species. Generally the pale western and red-backed cutworms are of economic importance in canola on the Prairies.
Use a garden trowel and soil sifter to collect cutworm larvae. Cutworms may be found in dry surface soil down to about two inches below the surface. The small, worm-like larvae curl up or attempt to hide in debris. Cutworm control may only be necessary in a limited area of the field. An insecticide is warranted when cutworms exceed three to four larvae per m2 and are actively feeding. Surface treatments should be applied in the evening, preferably under warm, moist conditions, because cutworms are active at night and these treatments will only control surface-feeding larvae.