SEASONAL OCCURRENCE OF LYGUS SPP. (HETEROPTERA: MIRIDAE) ON ALFALFA IN SASKATCHEWAN

Extract

Several species of Lygus (Hahn) that occur in Saskatchewan are serious and continuing pests of alfalfa grown for seed. They are readily controlled by any one of several insecticides, but the efficiency of this control is dependent upon knowing their seasonal development and occurrence on the crop.

In the years 1976 and 1978, at three locations in Saskatchewan, populations of Lygus in alfalfa seed crops were sampled at 5- to 7-day intervals throughout the period of insect activity. In 1979 and 1980 samples of bugs were taken occasionally from the same locations, and in all years from other locations in the province. A sample consisted of 0–700 specimens collected by either a 38-cm sweepnet in not less than 25 and as many as 200 random sweeps, or a D-Vac sampler in not less than 3 m² in spring and after harvest when sweep-sampling was not possible. Collected specimens were preserved in alcohol, sorted, and identified. Additional data, not previously published, were available from a similar mid-1950's study of Lygus seasonal occurrence in alfalfa seed crops in the Torch River district of northeastern Saskatchewan.