National Museum of Natural Science

Males of most stag beetle species occupy an area of tree trunk from which sap flows and attempt to mate with females foraging for food. Females prefer larger males (larger mandibles). However, medium- and small-sized individuals do possess mating strategies. For example, a medium-sized or small-sized male may use its mandibles to clamp the female, forcing her to keep moving, until she no longer puts up a resistance. As a longer time is required for mating than for larger males, if larger males are present, smaller males may move stealthily toward a female to try and find an opportunity to mate. 

Pictured here is Lucanus swinhoei Parry.

Image source: Provided by Huang Shi-Jie. 

Finding a mate