Epicauta pestifera
"Margined Blister Beetle"
Family: Meloidae

The margined blister beetle, Epicauta pestifera, is in the order Coleoptera (beetles), and in the blister beetle family, Meloidae. This beetle is economically important for several reasons. First, these blister beetles eat the leaves of a wide range of agricultural crops including alfalfa, clover, soybean, potato, tomato, cotton, and melon in addition to some ornamental plants. They are also important because they cause damage to livestock that are fed alfalfa if crushed beetles are in the hay. The beetles produce cantharidin, which is a toxin that causes inflammation in the gastrointestinal system. Cantharidin is highly stable which allows it to persist even after the beetle has been killed. Horses are very sensitive to this poison. In livestock the symptoms that may occur are colic, abdominal pain, depression, anorexia, Pollakiuria, and frequent urination. Livestock can be killed if enough of the toxin is consumed, but this is rare. Livestock are not the only things that can be affected by the poison. In humans if the beetle is crushed on the skin, blisters will form which can become infected if not treated.

The margined blister beetle ranges in size from a 1/2 inch to 1 1/4 inches. The head is wider than the thorax. The margined blister beetle is black and grey.

The margined blister beetle lays up to six masses of 50-300 eggs in the soil. Larvae of the beetle are pale and grub-like. Larvae in their first instar are mobile, but later instars tend to be sedentary. Larvae feed on grasshopper eggs. The larvae go through a series of six molts before overwintering in the soil in after the seventh molt in a pseudo-pupal stage. Only one generation of the beetles is produced each year. Adults generally emerge in late May and are active through the summer until September.

Control methods for the beetle are mainly cultural methods. In alfalfa one needs to harvest before the plant blooms because the beetles are attracted to the flowers and are generally not be in the field before that time. Weeds should also be controlled in order to keep the beetles out of the field since the beetles could be attracted to the weed flowers as well. Another way that the problem could be stopped is by using machinery that would not crush the beetles if they are present at harvest which causes the poison to get on the hay. Finally, if there is a large infestation one could use chemicals to kill the beetle causing them to fall to the ground and away from the crop.

Christopher Flick
Kevin Ott
Insect Biology and Diversity-Fall 2003