Cultural practices involve timing of cutting and modification of harvest equipment. Because blister beetles are attracted to flowers, cut the crop before bloom to reduce their presence in hay. It also is important to control flowering weeds and choose harvest equipment that gives the beetles the best chance of survival. Research at Kansas State University has shown that self-propelled swathers, without conditioning rollers but with windrowing attachments, are safer than mower conditioners and sicklebar mowers. Even with the conditionerless swather, avoid hay from the ends of the fields where the machine is turned around and beetles may be crushed by the tires.
Chemical control treats the crop just prior to harvest to eliminate beetle activity during harvest.
There is not much data on blister beetle control. Most recommendations seem to be based on preharvest intervals. Refer to 564A, High Plains Integrated Pest Management Guide , for future information on alfalfa insecticides. Select hay sources that have a low likelihood of blister beetle contamination. First cutting hay is the least likely to have beetles.