Blister Beetle

This Blister Beetle is feeding on Narrow-leaved Goldenrod. Scott King pointed it out to me on 12 August 2014, south of Northfield, Minnesota. Blister Beetles are in the family Meloidae, and are known to secrete a substance that causes skin to blister. Although this species is black, others of the 7500 species of Blister Beetles are aposematically colored, warning of their toxicity. Scott and I did not disturb this beetle.

Blister Beetle larvae are insectivorous, attacking bees and grasshoppers. Adults feed on a variety of flowers and leaves, including goldenrods.

Crushed Meloidid beetles are the principle irritant in folk medicine used as a male aphrodisiac. Not a good idea, since the arthropods have also been used to poison people. Some species are toxic to horses. A few beetles ingested with alfalfa hay can be lethal. Alfalfa should be carefully dried and treated (Wikipedia).