University of Illinois

No. 8/May 16, 1997

Anything New Regarding Alfalfa Weevils?

Figure 3 shows the actual heat-unit accumulations above a base temperature of 48 degrees F from January 1 to May 12, 1997. The map indicates that alfalfa weevil eggs should have hatched in virtually every county of Illinois. However, the development of the larvae is still slow because of the cool temperatures. Dave Dimmick with IMC Agribusiness observed small alfalfa weevil larvae in a field in northern Sangamon County on May 7. The density was nowhere near the economic threshold. Despite the fact that peak larval populations could have been observed already in the southern one-third of the state, economic levels of alfalfa weevils have not been observed in most fields. If luck remains with us, alfalfa weevils will not pose much of a threat to alfalfa production this spring.
Kevin Steffey, Extension Entomology, (217)333-6652