Wednesday, April 16, 2008

Lookout for Alfalfa Weevil in Ohio

Ohio State University Entomologists report that sufficient heat units have accumulated in southern Ohio to warrant growers to begin sampling for alfalfa weevils. Heat units at our weather stations in Piketon and Jackson are both over 300 as of this time. Central and/or northern Ohio has not reached 300 heat units , although it should reach that point by the end of the week in central Ohio, and not until next week for northern Ohio locations.

In Ohio, populations of alfalfa weevil seldom reach economic levels of abundance due to biological control by a complex of parasitic wasps and a fungal pathogen. However, damaging populations can occur and growers need to be alert and checking their fields weevils. This is especially true this year given the low supplies of hay and the high value of alfalfa on the market.

More information on the alfalfa weevil biology and management is available in OSU Factsheet FC-ENT-0032, Alfalfa Weevil, available at

For some excellent images and information on this pest, see the University of Illinois IPM website on Alfalfa Weevil at