Alfalfa weevils develop based on temperature or accumulating degree days. This cool spring has delayed all insect development, including alfalfa weevil. Scouting in alfalfa should begin at approximately 200 degree days for areas south of Interstate 80, and 250 degree days north of Interstate 80. Based on accumulated temperatures since January, weevils are active in southern Iowa now.
Iowa State University
Hodgson, Erin W. and Sisson, Adam J., "2013 Alfalfa Weevil Hatch Delayed" (2013). Integrated Crop Management News. 71.
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