Thanks to Scott Hartley who provided this update - Forest tent caterpillars have been reported in high numbers across the province of Saskatchewan, primarily in urban areas, parks and shelterbelts. Trees are the main host to this insect. Although there have been reports of the caterpillars in alfalfa and canola, feeding damage will not be significant.
Bacillus thuringiensis var. kurstaki (Btk) is the recommended control product as it is specific to moth and butterfly larvae (caterpillars). It is not considered dangerous to pollinators due to the ingestion mode of action and as they are in a different insect order the kurstaki strain of Bt is not toxic to the bees that may be foraging in flowering trees. Although other chemical insecticides are registered, they tend to affect a broad spectrum of insects including foraging pollinators.