History of the Alfalfa Weevil, Hypera postica (Gyll.) (Coleoptera: Curculionidae), in Alberta

Abstract

In June, 1954, the alfalfa weevil, Hypera postica (Gyll.), was found in very small numbers (one per 500 sweeps) in alfalfa fields in the valley of the Milk River and in the area between the hamlets of Onefour and Orion in southeastern Alberta. These were the first records of its occurrence in Canada. As the host-specific parasite Bathyplectes curculionis (Thoms.) (Townes and Townes, 1951) emerged from some of the weevil larvae collected then, the weevil had been in Alberta for at least one year. On July 26 an intensive search was made in the irrigated areas around Lethbridge. Only two weevils were taken in approximately 25,000 sweeps from 25 fields. The distribution of the weevil at this time indicated that it had migrated from the irrigated areas of Montana that lie along the lower reaches of the Milk River by way of the river valley.