Horned Bess Beetle

The Order: Coleoptera (beetles)

Family: Passalidae (bess beetles)

How to identify:

As with most insects, horned bess beetles have six legs and four wings. They are well known for their large, rounded bodies (1 ½ inch) made up of a hard, shiny black exoskeleton with parallel lines running down its back. Horned bess beetles have a prominent horn on the top of their heads and golden hairs lining different parts of their bodies. 

Advanced ID: Their thorax is smooth and parallel lines extend the length of the elytra. The pronotum has a distinct median groove, and mandibles are large, projecting forward. Antennae have 10 segments ending in a lamellate club (Bibbs et al, 2019).

Ecology

Metamorphosis Type: Complete metamorphosis

Geographic Range: Eastern and south-central North America

Habitat: Subtropical forests; inside or under plant matter and decaying wood where they create feeding tunnels.

Trophic Level: Herbivore

Food: Adults and larvae bess beetles feed on hardwood trees, including elm, oak, and other deciduous trees, using their thick mandibles. They cannot digest wood, but rather get their nutrients from the fungi on the wood they are eating. 

Why should we care?

Human Uses: The horned bess beetle helps with decomposition by breaking down dead materials found in the environment with help from both bacteria and fungi.

Conservation Status: Not endangered; however, they are facing habitat shrinkage and loss due to increased agricultural deforestation.

Did you know?

• Listen closely, and you might hear both the larvae and adults making up to 17 different acoustic signals (Bibbs et al, 2019).
• Bess beetles are able to pull 50 times their own weight (Davis, 2014)

Researcher’s Biography

Michael Hoban
Completed this research within Dr. Shelly Thomas’ Entomology course.

Suggested Citation:

Hoban, Michael. (2021). Horned Bess Beetle. Rowan University Arboretum. https://arboretum.rowan.edu/learn/explore-insects/horned-bess-beetle/