Ebony Blister Beetle

Larvae of the genus Epicauta are considered beneficial because they impact grasshopper populations, but adults can damage crop, and the cantharidin they contain is toxic to vertebrates, especially horses. Several species feed on alfalfa, so there is a danger of beetles contaminating hay that is fed to domesticated animals.

All larval instars and both sexes of Epicauta funebris produce cantharidin. The first five larval stages accumulate cantharidin as they feed and grow. They exude the substance in a milky oral fluid when disturbed. Only males continue to produce the compound in the adult stage. Adult males transfer cantharidin to adult females in spermatophores during mating. Adult beetles usually respond to disturbance by feigning death and bleeding cantharidin-lade... read moren hemolymph from certain leg joints.

The ebony blister beetle is among the most pestiferous species of Epicauta. Although the larvae consume of eggs of the differential grasshopper (Melanoplus differentialis) and perhaps some other pest species, the adults are sporadic pests of garden, truck, and field crops in Arkansas, and they have been known to defoliate tomatoes and swiss chard here. Other hosts include Irish potatoes and clematis, plus some wild plants.

The black form of E. funebris occurs in the Southwest, primarily from Texas and eastern Louisiana north to southern Kansas. E. funebris is easily separated from E. cinerea by the enlarged maxillary palp and the form of the antenna (Pinto 1991). The black form of E. funebris can also be confused with E. pensylvanica, but in E. funebris the third segment of the maxillary palp is longer than the width of the eye. In E. pensylvanica it is shorter than the width of the eye.