Horned passalus (larvae, pupa, and adult)

These beetles are shiny black and have many long grooves on their elytra (outer wings). They have a small horn between their eyes, and clubbed antennae. 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, possibly to communicate danger to other beetles.

Patent-leather beetles are usually found under, or inside, old logs or stumps. They eat old decaying wood. These beetles make tunnels in the wood, called "galleries." Inside the galleries, the beetles will mate, lay eggs, and raise their young. Larvae hatch from the eggs; they look like white grubs. The adults feed the larvae a chewed-up mixture of wood chips and feces. The larvae cannot feed themselves. Patent-leather beetle larvae take a year to develop. When the larvae are ready, they become pupae. Adults hatch from the pupa. Adult beetles are often covered by mites.