OSU entomologists have not collected adult striped beetles before mid-May. Usually, the adult blister beetle does not become active until mid-June in Oklahoma. Similarly, hay harvested late in the season generally is free of beetles, as insect activity ceases in early fall. However, El Nino already has been shown to have altered weather conditions in the state, and the changes in weather conditions may be enough to speed up or put off beetle appearance in alfalfa fields. Freeman said scouting programs prior to cutting can be helpful.
Blister beetles tend to congregate in large numbers in small areas.
Spraying fields with a short residual insecticide just prior to harvesting to kill beetles also can be an effective tool to reduce the presence of beetles. Regardless of scouting or spraying measures, most hay contaminated with blister beetles is the result of the beetle being crushed during the harvesting process. The crimper-roller kills the beetles, and the remains are left in the hay. As such, cutting without using crimpers decreases the chance of equine ingestion of beetles. It is common for many of the live beetles to leave the area shortly after cutting.