Adult alfalfa weevils 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 could be active throughout Iowa (Fig. 1).
Iowa State University
Hodgson, Erin W., "Alfalfa Weevils Active Throughout Iowa" (2015). Integrated Crop Management News. 310.
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