HORNED PASSALUS BEETLE

Odontotaenius disjunctus

PASSALID BEETLE FAMILY (Passalidae)


Description
The adult beetles range from about 1 1/8 to 1 5/8 inch in length and are shining black with a series of grooves running the length of the wing covers (elytra) and a short horn on the front of the head between the eyes. Immature beetles are similar to "white grubs. The red beetles in photos B. and E.are immature beetles just after emergence from the pupa form. Photo C shows the beetle with mites on the head.

Occurrence
The horned Passalus is common and widespread in the eastern U.S. We suspect it is also common in Fontenelle Forest but are not sure. This beetle occurs mostly in decaying logs, often in large numbers. All stages of its life live together in decomposing logs. Wood infested by these beetles is usually well decomposed and falls apart readily. They are usually seen during the day as they climb on logs.

Comments
These beetles are often called Bess beetles and sometimes patent leather beetles because of their shiny bodies.This beetle is considered beneficial because it decomposes dead wood. It is medically harmless. When disturbed, adults produce a squeaking sound by rubbing their wings on the abdomen. This is apparently used for communication between members of the colony. Some fourteen different sounds are known,more than many vertebrates. The adult beetles are often covered by mites (see photo C). Adults tend and feed larvae, preparing food with salivary secretions. Food consists of decaying plant matter. Some stag beetles are similar but they never have a horn and their antennae are elbowed. This beetle is one of a very few species of passalids which have developed the ability to withstand freezing temperatures accounting for its wide distribution.



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Horned Passalus

Horned Passalus

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