Bess Beetle | Vol 3, No. 11

Odontotaenius disjunctus

Order: Coleoptera
Family: Passalidae

If you have ever dug into a rotting hardwood log or stump, you may have encountered bess beetles. Actually, their approved common name is horned passalus, but these beetles have several colloquial names, including pinch beetle, bess bug, betsy beetle, bessie beetle, and patent leather beetle. Trying to keep up with all of these different names could drive one “crazy as a betsy bug.” Most southern gardeners are more likely to recognize the name bess beetles, or some derivative thereof, rather than horned passalus. They get this last name from a single small horn that occurs in the center of the head of adults of both sexes.
 
Adult beetles are easy to identify by their large size, about 1 ¼ inch, and patent-leather-shiny black body color. The thorax is smooth, but the wing covers over the abdomen are covered with parallel ridges.  The larvae have elongate translucent-white bodies with tan-colored heads. Bess beetle larvae only have four functional legs. The third pair of legs is reduced to a short peg that is used as a sound-making device. Unlike most beetles, bess beetles are considered to live in a type of semi-social relationship because the larvae feed on a mixture of feces and sawdust produced by the adults and because adult females and males work together to produce this food and care for larvae.
 
One of the more interesting traits of bess beetles is that both the adults and larvae are able to produce sounds. Hold an adult beetle near your ear and you can easily hear the squeaking sound they make to indicate they are unhappy with the situation. The larvae make sounds to communicate with the adults and let them know they are hungry. Young adult beetles leave the log in which they developed to go on mating flights and then search for a new decaying log to begin their own brood. Bess beetles play a beneficial role in the environment by helping recycle dead logs and stumps.