Stag Beetles, Family Lucanidae

Habits and Traits of Stag Beetles

Stag beetle.
Stag beetle. Getty Images/Biosphoto/Christophe Ravier

Stag beetles are some of the biggest, worst bugs on the planet (at least they look bad!). These beetles are so named for their antler-like mandibles. In Japan, enthusiasts collect and rear stag beetles, and even stage battles between the males.

Description

Stag beetles (family Lucanidae) do get quite large, which is why they are so popular with beetle collectors. In North America, the largest species measures just over 2 inches, but tropical stag beetles can easily top 3 inches.

These sexually dimorphic beetles also go by the name pinch bugs.

Male stag beetles sport impressive mandibles, sometimes as long as half their body, which they use to spar with competing males in battles over territory. Though they may look threatening, you don't need to fear these enormous beetles. They're generally harmless but may give you a good nip if you try to handle them carelessly.

Stag beetles are typically reddish-brown to black in color. Beetles in the family Lucanidae possess antennae with 10 segments, with the end segments often enlarged and appearing clubbed. Many, but not all, have elbowed antennae as well.​

Classification

Kingdom – Animalia

Phylum – Arthropoda

Class – Insecta

Order – Coleoptera

Family - Lucanidae

Diet

Stag beetle larvae are important decomposers of wood. They live in dead or decaying logs and stumps. Adult stag beetles may feed on leaves, sap, or even honeydew from aphids.

Life Cycle

Like all beetles, stag beetles undergo complete metamorphosis with four stages of development: egg, larva, pupa, and adult.

Females usually lay their eggs under the bark on fallen, rotting logs. The white, c-shaped stag beetle larvae develop over one or more years. Adults emerge in late spring or early summer in most areas.

Special Adaptations and Defenses

Stag beetles will use their impressive size and massive mandibles to defend themselves if needed. When it feels threatened, a male stag beetle may lift its head and open its mandibles, as if to say, "Go ahead, try me."

In many parts of the world, stag beetle numbers have declined due to forest defragmentation and the removal of dead trees in populated areas. Your best chance of seeing one may be observing one near your porch light on a summer evening. Stag beetles do come to artificial light sources, including light traps.

Range and Distribution:

Worldwide, stag beetles number around 800 species. Just 24-30 species of stag beetles inhabit mostly forested areas of North America. The largest species live in tropical habitats.

Sources

  • Borror and Delong's Introduction to the Study of Insects, 7th Edition, by Charles A. Triplehorn and Norman F. Johnson

  • Insects: Their Natural History and Diversity, by Stephen A. Marshall

  • Stag Beetles of Kentucky, University of Kentucky Entomology Department