Stag beetles.

Stag beetle, (family Lucanidae), any of some 900 species of beetles (insect order Coleoptera) in which the mandibles (jaws) are greatly developed in the male and resemble the antlers of a stag. In many species the elaborately branched and toothed mandibles may be as long as the beetle itself. If handled carelessly, their pinch can draw blood from a person. In some cases, however, the mandibles are large enough to be a handicap to the beetle’s movement.
Female stag beetles are usually smaller than the males, with smaller mandibles that are much more powerful than the males'.[3] As larvae, females are distinguished by their cream-coloured, fat ovaries visible through the skin around two-thirds of the way down their back.
The Most Expensive Insect in the World