Blister Beetles? Look Again - U of I Extension

News Release

Blister Beetles? Look Again

This article was originally published on May 30, 2011 and expired on June 6, 2011. It is provided here for archival purposes and may contain dated information.

Each year Extension reminds producers to watch out for blister beetles. Blister beetles contain a chemical termed cantharidin that can prove life-threatening for horses consuming blister beetle-contaminated hay. Cantharidin is a blistering agent.

Spraying for blister beetles is not a solution since a dead beetle still contains cantharidin, thus still posing a threat. Extension recommends scouting in an attempt to avoid accidentally baling infested regions and feeding infested hay. We also recommend that producers only target the first cut and very early second cut for horses since blister beetles usually are not prevalent at those times. However, calendar dates do not eliminate the need for scouting.

While there are different blister beetle species, all tend to have some common traits. First, blister beetles feed in mass in relatively small areas of a field (often not much more than a few feet in diameter). Leaves are stripped back to the main veins and plants are "speckled" with glossy, dark green to black-colored droppings. Secondly, blister beetles resemble one another in their general "shape." Like all insects, blister beetles have three body regions called the head, the thorax (region just behind the head), and the abdomen. In blister beetles the thorax is less wide than the head giving the insect a "long necked" appearance.

In early June, Extension begins to receive its first "blister beetle" reports of the season. But, there is a problem, the calls we receive are often not really about "blister beetles." Instead, many confuse blister beetles with a "very rough" look-alike.

Soldier beetles, the look-a-likes in question, are a half-inch long when full grown. While species color variations exist, most reports to our office pertain to "an orange-colored insect with black markings." These orange-colored soldier beetles have a black stripe on the thorax directly behind the head, as well as a stripe on each wing cover. The claim to fame for these insects is often their habit of appearing in large numbers where flowers are present. Linden trees are very attractive to them.

Soldier beetles differ from blister beetles in some significant ways. First, they do appear long and thin, much like a blister beetle, but they are smaller and definitely do not have a "long neck." In other words, the thorax is as wide, and possibly wider, than the head. Second, soldier beetles do not feed on leaf tissue. Instead, adult soldier beetles feed on the nectar and pollen of many flowering plants (golden rod for instance) and sometimes the adults will even consume aphids. Blister beetle adults are strictly leaf feeders, but their young will prey on grasshopper eggs while in the soil. Soldier beetle larvae feed on a wider range of insect stages, including maggots, caterpillars, eggs, etc. Finally, soldier beetles do not contain cantharidin so they pose no threat to livestock. While blister beetles are a concern, soldier beetles are no more than a curiosity.

Programming Reminder – Area residents are invited to attend a Pond Management Seminar held from 4 - 9 p.m. on Monday, June 13, 2011 at Ossami Lake Beach, 210 Northshore Drive, Morton. Presentations will be offered from 5:30 - 7:30 p.m. and include the following speakers/topics:

"Pond Ecology and Pond Construction" - Duane Friend, University of Illinois Extension

"Nitrogen and Phosphorus" - Matt Montgomery, University of Illinois Extension

"Pond Management and Aquatic Vegetation" - Wayne Herndon, Illinois Department of Natural Resources

Ossami Lake Homeowners Association will offer vendors, and the Illinois Environmental Protection Agency will also provide a children's activity center.

Register at or by calling 309-347-6614 by June 10, 2011.

Source: Matt Montgomery, Extension Educator, Local Food Systems and Small Farms,

Pull date: June 6, 2011