The bertha armyworm, Mamestra conjigurata Wlk., is a polyphagous climbing cutworm (Lepidoptera: Noctuidae) that attacks canola (Brassica napus L. and B. campestris L.) in the prairie provinces of Canada. Following the outbreaks of 1971–1974 (Turnock and Philip 1977), sampling methods to determine larval density in the field were developed by researchers in Manitoba, Saskatchewan, and Alberta. The methods were basically similar, using a 3-sided metal frame to outline each 0.5-m2 sample unit, with the long side of the frame (1 m) parallel to the rows of the crop. The differences were in the way in which the plants and soil surface were searched for larvae. In Manitoba, the plants within each sampling unit were shaken by hand, then the soil surface was examined for larvae and earthen lumps and plant debris were moved to expose hidden larvae. In Saskatchewan, the plants were shaken, then cut near the base and discarded before the ground surface and debris were searched. In Alberta, the plants were cut near the base, then shaken over a sheet, and the sheet and ground surface were examined for larvae.