Russian wheat aphid, Diuraphis noxia, was first detected in Canada in late July 1988 when a few were found on late-maturing spring cereals in southern Alberta near the International Boundary between Coutts and Aden. By the end of September, after dispersal or further immigration influx, it was widespread in Alberta south of Highway #3 and in southwestern Saskatchewan as far east as Swift Current. By mid-October more than 30% of the plants in many fields of winter wheat and fall rye in southern Alberta and up to 20% of plants in some fields of fall rye in southwestern Saskatchewan were infested. In November, Russian wheat aphid was also found on winter wheat in the Creston Valley of British Columbia.