Scouting for alfalfa weevil larvae is not that difficult, although it takes several minutes when done properly. In any alfalfa field, I prefer to start my scouting with a sweep net. A sweep net and a quick and easy method of answering the question, "are there alfalfa weevil larvae in the field?" By taking 40-50 sweeps in an area, it can easily be determined if larvae are present or not. If larvae are found, then proceed to the stem-sampling technique, which is used to determine the economic threshold. Stem sampling can more accurately determine the population size and the potential for yield loss.
Iowa State University
Rice, Marlin E., "Scout first and then decide: Using economic thresholds for alfalfa weevils" (2007). Integrated Crop Management News. 1106.
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