Texas Cooperative Extension, Texas A&M University System
Department of Entomology, Texas A&M University
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Horned Passalus or "Betsy" Beetle
Horned passalus or betsy-beetle, Odontotaenius disjunctus (Illiger). Photo by Drees.
Click on image to enlarge
Horned passalus
or betsy-beetle,
Odontotaenius disjunctus
(Coleoptera: Passalidae).
Photo by Drees.

Common Name: Betsy beetle
Scientific Name: Odontotaenius disjunctus (Illiger)
Order: Coleoptera

Description: Adult beetles are up to 1-3/8 inches long, 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" (Coleoptera: Scarabidae). However, larvae only have two pairs of true legs and grow to about 1- inches long.

Life Cycle:Adults and c-shaped grubs occur together in decomposing logs. Larvae probably take at least a year to develop.

Habitat and Food Source(s): Mouthparts are for chewing. Passalid beetles are somewhat social insects, which colonies living in galleries (tunnels) in decaying logs and stumps. Wood infested by these beetles is usually well decomposed and falls apart readily. Adult Passalus beetles are often covered by mites. Adults tend and feed larvae, preparing food with salivary secretions. Food consists of decaying plant matter. 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.

Pest Status: Occurs in decaying logs, often in large numbers; considered beneficial in its activities to decompose dead wood; medically harmless.

Management: None, considered beneficial.

For additional information, contact your local Texas A&M AgriLife Extension Service agent or search for other state Extension offices.

Literature: Borror et al. 1989.

From the book:
Field Guide to Texas Insects,
Drees, B.M. and John Jackman,
Copyright 1999
Gulf Publishing Company,
Houston, Texas

A Field Guide to Common Texas Insects, Bastiaan M. Drees and John A. Jackman.


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