Stag Beetle

They can pinch, but it is rarely a problem. In the male, the giant antler-like jaws are mostly for display and wrestling and are too long and lightly muscled to deliver a strong bite, so a male gripping a finger produces a firm but mild pinch. The female has much smaller jaws that are far more powerful, and a large female can give a nip that draws a bead of blood if she is handled roughly, though she will usually only do so in defence. Neither sex is venomous or dangerous, and stag beetles do not seek out people. If one lands on you, letting it walk off or gently lifting it by the sides of the body avoids any pinch.

They are a product of sexual selection through male combat. Male stag beetles fight each other for access to the sap runs where females gather and for the females themselves, and the fight is a wrestling contest in which each male tries to get his jaws around the other and lever him off the branch or turn him over. A male with longer, better-shaped jaws has more reach and leverage and wins more contests, so over evolutionary time the jaws have been pushed to an extreme size, up to half the beetle's body length. The trade-off is that the jaws are so large they are structurally weak and a drain to grow, and males in poorly fed larval conditions develop only small jaws.

The single most useful thing is to leave dead wood in place. Stag beetle larvae need buried and partly buried decaying broadleaf wood, especially oak, so keeping old tree stumps in the ground rather than grinding them out, letting fallen logs and branches rot where they lie in a quiet corner, and building a simple log pyramid by partly burying chunks of untreated hardwood all provide breeding habitat. Avoid disturbing the soil around known stump sites, keep pesticide use down, and be careful with cats at dusk in early summer when adult males are flying. Reporting sightings to a local recording scheme also helps track the population.

All are large beetles in which males carry oversized weapons used in fights over females, but the weapons are different structures. A stag beetle's weapons are its mandibles, the jaws, enlarged into antlers that grip and wrestle. A rhinoceros beetle or Hercules beetle carries horns, which are outgrowths of the head and thorax, not jaws, and it uses them to pry and flip a rival rather than to grip him. Rhinoceros and Hercules beetles belong to the scarab family and are generally heavier-bodied, while stag beetles are in their own family, the Lucanidae. The two groups are a nice example of the same evolutionary pressure, competition among males, producing different solutions.