Bess Beetles (Passalidae)

Bess beetles are unique among insects as they care for their young and help raise them till adulthood, behavior uncommon to beetles. There are around 500 species of these beetles worldwide, mostly in tropical areas but also in North America.

Common Beetles Belonging to this Family

Scientific Classification

These beetles are classified into several genera.

  • Aceraius
  • Aulacocyclus
  • Ceracupes
  • Chondrocephalus
  • Cylindrocaulus
  • Didimus
  • Heliscus
  • Leptaulax
  • Odontotaenius
  • Ogyges
  • Oileus
  • Passalus
  • Paxillus
  • Pentalobus
  • Petrejoides
  • Popilius
  • Proculus
  • Ptichopus
  • Publius
  • Spasalus
  • Spurius
  • Verres
  • Veturius

Physical Description and Identification


Size: 0.78-1.69 in (2-4.3 cm)

Color: These beetles are black, with yellow setae ventrally.

Other Characteristic Features: Their bodies are elongate-cylindrical, with a single horn on top of their heads and antennae that consist of 10 feelers and a 3-segmented club. They can produce up to 14 acoustic noises by rubbing their hindwings against the upper abdomen, which is more than most vertebrates.

These beetles are relatively social compared to similar insects, living in colonies alongside their young.


Large white grubs that produce a squeaking sound while moving by rubbing their third leg against a striated area of their second leg. Their parents will provide them with nourishment during this phase.


Adults and other juveniles help the larvae prepare for pupation by constructing their cocoons out of frass. The beetles guard the pupae in their colonies until they are ready to emerge.


Females lay eggs inside tunnels excavated within rotting wood.

Quick Facts

Other names Bessbugs, betsy beetles, horned passalus beetles
Lifespan 1 year
Distribution Tropical parts of the world
Habitat They spend their lives in the dark, in places like rotten tree trunks.
Seasons active March-June
Host Plants Hardwood trees like oak and elm
Diet Larvae: A mixture of the adults’ feces which consists of decaying wood and fungi

Adults: Rotting wood and moss, which they re-consume after excreting to absorb nutrients

Identifying the Damage Caused by Them

As decomposers, they do not cause any harm to crops or humans. Generally docile, even a pinch from their mandibles isn’t considered deadly.

Did You Know

  • English zoologist William Elford Leach, MD, FRS, first described this family of beetles in 1815.