What is growing on top of a stag beetle's head?
The most distinctive feature of the male stag beetle is its large mandibles. These are genuine "teeth", and make up a portion of the mouthparts. These are different from the "horns" that grow on the top of or in the anterior portion of the head of rhinoceros beetles or numerous scarab beetle species. At the base of the mandible is a pair of joints that allow it to move horizontally in a certain direction (without rotation). Horns are fixed, and the entire head must be moved to control their direction. When stag beetles fight, they bite one another. However, rhinoceros beetles and scarab beetles butt or ram their opponents with their horns.
Pictured here is a male Dorcus schenklingi (Möllenkamp). This is a large stag beetle with mandibles shaped like crescent blades. So, it is sometimes referred to as crescent blade or warrior beetle.
Image source: Provided by Huang Shi-Jie.
