Horned passalus beetle
This beetle communicates with its grubs using at least fourteen distinct rasping sounds, more than any other known arthropod.
| Where | Decaying logs in deciduous forests |
|---|---|
| Size | 30 to 40 mm body length |
| When | March to November |
The Horned passalus is a large, glossy black beetle with deeply grooved wing covers and a short horn that curves forward above the head. Its antennae end in a lamellate club and are not elbowed, which separates it from the stag beetles it is sometimes mistaken for.
Adults and larvae live together inside rotting hardwood logs, where the adults chew wood into a soft pulp to feed the growing grubs. Newly matured adults leave the log on a nighttime dispersal flight to found a new colony, and are occasionally drawn to lights during this flight.
Traits
Habitat
Woodland
Colour
Black
Active
Night
To people
Considered harmless to handle, though it can deliver a mild pinch with its mandibles if picked up.
Activity through the year
Often confused with
Nearly identical in size at about 30 to 40 mm, but with noticeably wider front tibiae and a shorter, less prominent horn, and restricted to central and southern Florida.
Questions
Is the Horned passalus beetle dangerous to people?
Considered harmless to handle, though it can deliver a mild pinch with its mandibles if picked up.
When can you see the Horned passalus beetle?
The Horned passalus beetle can be seen from March to November, at night.
Plate retouched from a photo by Wendy McCrady, CC BY 4.0, iNaturalist Licence
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Beetles›Passalidae›Odontotaenius
Last updated 2026-09-26. Every entry is checked against published sources.