Plant matter, leaves, fruit, seeds and wood are the most common staples in the beetle's diet. They also commonly eat fungus and decaying organic matter, such as dung and carrion. Some beetles, such as rove beetles or ground beetles, are predatory carnivores, meaning they hunt and eat other creatures.
While most beetles are not picky eaters, some eat only particular species of plants or animals. Longhorn beetles, weevils and leaf beetles tend to be host-specific when it comes to the plants they eat.
Earthworms and snails are common prey for carnivorous beetles. Ants are another common food source for beetles, and there are over 1,000 different kinds of beetles that are parasitic, predatory or commensal, meaning they benefit from a relationship with another species while the other species is unaffected, in ant communities. Some beetles are ectoparasitic, meaning they live on the skin of a mammalian host and feed on skin tissue and secretions.
Honey bees are another food source for parasitic beetles, such as the small hive beetle. The larvae infiltrate the beehive and destroy the comb by tunneling through towards the honey. This is a problem for many beekeepers because the dung from the beetles taints the honey and often causes the bees to abandon the nest.