Diet

• Adults: Feed primarily on decaying wood, which they chew and process with their powerful mandibles. They also consume fungi and microorganisms associated with decomposing wood.

• Larvae: Feed on wood that has been partially processed by the adults. The larvae depend on adults to prepare suitable food from the tough woody material.

• Adults and larvae live together and cooperate in processing their food, making Passalinae unusual among beetles.

Range

• Passalinae is the principal subfamily of bess beetles (Passalidae) and is especially diverse in tropical and subtropical forests of the Americas.

• Bess beetles can be found around Zihuatanejo, particularly in areas containing substantial amounts of moist, decaying hardwood.

• Around Zihuatanejo, they are occasional to fairly common in suitable forest habitat, but are much less likely to be encountered in dry, open areas without rotting wood.

Habitat

• Primarily associated with fallen logs, rotting stumps, decaying branches and downed hardwood.

• In the Zihuatanejo area, the best places to look are moist tropical forest, shaded ravines and areas where fallen trees remain on the forest floor.

• They are often found inside the wood rather than on its surface, so splitting or examining well-decayed logs can reveal adults, larvae and their galleries.

Size

• Adult length: approximately 15–40 mm (0.6–1.6 in), depending on species.

• Body robust, elongated and usually glossy black.

• The head has powerful mandibles and a prominent horn or projection in many species.

• The elytra are strongly grooved, and the antennae have distinctive lamellate clubs.