San Diego Natural History Museum--Your Nature ConnectionSDNHM Field Guide
Darkling Beetle (Coelocnemis californicus)

Eleodes spp.
Darkling Beetle

Family: Tenebrionidae


The darkling beetle is a common named assigned to various members of the family, Tenebrionidae. Also known as stinkbugs, these beetles are dark brown to black with hardened front wings that are not used in flight. The antennae, which arise from under a ridge near the eyes, have many segments and are enlarged near the tip. Darkling beetles are about one inch in length. The larvae are a type of mealworm. They average an inch in length and have a tough, yellowish brown exoskeleton.

Range and Habitat

Darkling beetles are found throughout the world in a wide range of habitat types. Mealworms dark places and can be found under rocks, and logs, in animal burrows and in stored grains.

Natural History

Darkling beetles are considered decomposers and eat decaying leaves, sticks and grasses. They also feed on dead insects, feces, and stored grains. There are many natural predators to the mealworms including rodents, lizards, predatory beetles, spiders, and birds.

When threatened, the darkling beetle assumes a defensive posture by standing on its head and emitting a foul-smelling liquid composed of compounds called quinones.

Impact on Ecosystem

Darkling beetles consume dead and decaying organic material and play an important role in the decomposition process. However, mealworms are also considered pests because they infest and consume stored grains.

Text by Connie Gatlin
Photo credit: Jim Melli

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