Page 2 | Blister Beetles in Alfalfa Hay | Horse Articles

Identify the species of blister beetles.
Grow your own alfalfa and maintain complete control over management practices, if possible.
Because blister beetle populations are not large until mid- to late summer, set aside first and often second cutting hay for use in feeding horses. Or consider purchasing first cutting hay from neighbors to use as horse feed.
Watch for beetles as you cut hay. Some species "swarm" in front of the harvester. Stop and let the beetles disperse before continuing.
Crimping and other conditioning increases the number of beetles that remain in the swath prior to baling. If possible, try to cut the alfalfa and put in swaths that can be straddled by the tractor to avoid crushing beetles in the windrow.
Eliminate weeds and cut the alfalfa before it reaches advanced bloom stages. Flowering plants attract the beetles that feed on alfalfa and weed pollen.
Insecticide treatments are available but must be applied with preharvest intervals in mind. If you treat with insecticides, be sure to allow enough time so that dying beetles fall out of the canopy to the ground where they burrow into the soil. Do not treat fields at peak bloom to avoid bee kills and losses to other beneficial species.

Because the larvae of many blister beetles in the genus Epicauta eat only grasshopper egg pods, these blister beetles are often associated with grasshopper outbreaks. Alfalfa grown near rangeland has a greater likelihood of blister beetle infestation. Blister beetles are especially attracted to alfalfa and weeds (e.g., goldenrod) during bloom.