Blister beetles keeping busy

Several reports of blister beetles are coming in from homeowners, vegetable producers, and row crop farmers this week. Although the adults are not generally considered plant pests, it appears decent numbers are causing some injury this summer.

Adult blister beetles can be commonly seen on plants within Amaranthaceae, Apocynaceae, Fabaceae, and Solanaceae families. It is easy to find them on bean, beet, carrot, cabbage, chili pepper, Chinese cabbage, corn, eggplant, melon, mustard, pea, pepper, potato, radish, spinach, squash, sugar beet, sweet potato, tomato, and turnips. Alfalfa, clover, and soybean can also be attacked; but pigweed, horsenettle, and black nightshade are probably their favorites.

Most of the time, they will move on quickly and not create significant injury. The bigger problem is when they are accidentally consumed by animals or contact skin. Read more about management in alfalfa hay here.

There are at least four species in Iowa, including a) black, b) ashgray, c) margined, and d) striped. Photos by a) Joseph Berger, b) Whitney Cranshaw, c) Clemson University, and d) Clemson University at www.ipmimages.org. Adults are typically active May - October but the highest numbers are observed in July and August. The most common plant defoliator is the striped blister beetle. These beetles tend to aggregate and form swarms and are more likely found along field edges. The adults are easily disturbed and attempt to fly away if they sense motion from people or machinery.