Giant Stag Beetle (Elk Stag Beetle)

Photo of a male giant stag beetle on moss
Scientific Name
Lucanus elaphus
Lucanidae (stag beetles) in the order Coleoptera (beetles)

The giant stag beetle is enormous, the males reaching 1½ inches in length without the mandibles, and nearly 2½ with them. Females might be confused with females of the reddish-brown stag beetle but have darker legs and a smooth thorax shield.

Look for the giant stag beetle on rotting logs in deciduous forests in early summer, where males combat each other for prime mating locations and opportunities. They’re also attracted to lights (yes, they can fly), so you may find one on its back on the morning, under a streetlight. They are sometimes discovered in pools.

By the way, the scientific name elaphus is from the Greek word for “stag” (deer), not for “elephant.” But with their large size and tusk-like (though toothed) horns, it's understandable why people would call it the elephant stag beetle.

Eggs are deposited into the cracks in the wood of damp, rotting, fallen trees. Larvae are C-shaped grubs that eat decaying wood of decomposing trees and stumps and take at least one year to develop to maturity. As an adult, this beetle lives for only a few months. Adults sustain themselves by eating the juices of plants, rotting fruits, and perhaps also aphid honeydew.

Learn more about this and other stag beetles on their group page.

Other Common Names
American Stag Beetle
Elephant Stag Beetle

There has been some concern about the conservation status of this, one of the most spectacular beetles in North America, especially since there's been a well-documented decline of a closely related species in Europe. A 2017 U.S. study provided details about the habitat and other needs for this beetle's reproduction and development. The study concluded by recommending conservation of existing lowland deciduous forests with plenty of nicely rotting dead logs lying undisturbed on the ground.

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About Land Invertebrates in Missouri
Invertebrates are animals without backbones, including earthworms, slugs, snails, and arthropods. Arthropods—invertebrates with “jointed legs” — are a group of invertebrates that includes crayfish, shrimp, millipedes, centipedes, mites, spiders, and insects. There may be as many as 10 million species of insects alive on earth today, and they probably constitute more than 90 percent all animal species.