Even though it was an extremely cold winter, some alfalfa weevil adults are expected to survive. Adults will begin moving as soon as temperatures exceed 48°F and begin laying eggs in alfalfa. Alfalfa weevil eggs develop based on temperature, or accumulating degree days, and hatching can start around 200-300 degree days. Start scouting alfalfa fields south of Interstate 80 at 200 degree days and fields north of Interstate 80 at 250 degree days. Based on accumulated temperatures since January, weevils are active in southern Iowa now and scouting to monitor for larval activity should start in southwestern Iowa this weekend (Fig. 1).
Iowa State University
Hodgson, Erin W., "Start Scouting for Alfalfa Weevil with Updated Economic Thresholds" (2014). Integrated Crop Management News. 102.
The Iowa State University Digital Repository provides access to Integrated Crop Management News for historical purposes only. Users are hereby notified that the content may be inaccurate, out of date, incomplete and/or may not meet the needs and requirements of the user. Users should make their own assessment of the information and whether it is suitable for their intended purpose. For current information on integrated crop management from Iowa State University Extension and Outreach, please visit https://crops.extension.iastate.edu/.