University of Maryland Extension

Blister Beetle - Flowers

blister beetle

There are 250 species of blister beetles in the U.S. The name blister refers to the chemical cantharidin in their bodies. This chemical will blister the skin if the beetle is crushed against it. The adult beetles are 1/2 to 3/4 inch long, slender and the elytra or wing covers soft and flexible. The color may be black or gray, brown or yellow and sometimes striped or margined. They feed on flowers and foliage of a wide variety of plants including aster, calendula, Japanese anemone, chrysanthemum, gladiolus, dahlia, dianthus, delphinium, phlox, and zinnia. Blister beetles are unusual in their life history. The larvae are predaceous (they feed on eggs of grasshoppers), but the adults are plant feeders.

black blister beetle closeup
Black blister beetle


Handpick the beetles to control small numbers. Wear gloves to protect the skin.

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