Biological Control of the Alfalfa Weevil, USDA-APHIS Program Aid No. 1321.

The alfalfa weevil is the most serious pest of the nation's leading crop for hay. In it's native Europe several parasitic wasps hold it in check. From 1911 to 1953 limited numbers of European parasites were introduced into the western United States, and in 1959 larger quantities of wasps were imported into the East. An intensive program of survey, release, and evaluation was conducted from 1980-1991 to help distribute the wasps to everywhere alfalfa is planted. Today many growers do not need to apply insecticides for alfalfa weevil control because of successful biological control.

Several types of ornamental Euonymus plants are susceptible to damage by the euonymus scale, an insect pest that tends to be more severe in warmer climates. Both the pest and the natural enemies imported to control it are from Asia. A species of lady beetle from Korea, Chilocorus kuwanae, has been very effective in reducing or even eliminating heavy scale populations in many locations. Other predators and parasitic wasps are also being evaluated for introduction as part of a nationwide USDA biological control project.