The map below indicates the accumulated degree days for each of the nine Iowa crop reporting districts. Degree-day information indicates that alfalfa weevil larvae should be hatching this week in southern Iowa. In central Iowa counties, weevils should be hatching by the third week of April; and in northern Iowa, weevils should hatch the last full week of April. That means that fields in southern Iowa should be scouted now.
Iowa State University
Pope, Richard O. and Tollefson, Jon J., "Alfalfa Weevil Hatch is Upon Us" (2009). Integrated Crop Management News. 699.
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