The greater stag beetle (scientific name: Lucanus cervus) is the largest terrestrial insect in Europe. Its common name derives from the enlarged mandibles (jaws) in the males of this species, which look like the antlers of a stag. In fact, they are used for a very similar purpose. Males use their large mandibles to fight each other for a mate (or mating spot), very much like deer use their antlers.
Females are smaller in size, and do not have such large mandibles. They lay their eggs in pieces of decaying wood, on which the larvae then feed. It can take up to three years for a stag beetle to become an adult. These adults then emerge in late spring or early summer, and typically only live for a few weeks, during which they mostly feed on plant sap. Despite their large size (and weight), greater stag beetles can actually fly, which they preferably do in the evenings in search for a mate.
L. cervus is quite common in much of Europe, although in serious decline in some countries. This is largely due to the disappearance of natural primary forests in some regions. Its predators include corvids such as crows and magpies. These birds especially like to eat the abdomen (the third and largest body part) of stag beetles, which is rich in fat that was accumulated during the larval stage. As a result, finding a greater stag beetle corpse consisting of only the head and thorax is not uncommon.
What is perhaps much more rare, is to find one that is still moving! I recently came across such a (somewhat disturbing) sight along one of my walks through the Wienerwald (the forest along the western side of Vienna, Austria). It was a male greater stag beetle with its abdomen missing, but with the remaining pair of (front) legs and mandibles still moving…
The poor thing must have just been eaten by a crow, which are very common in these forests. Well, it’s all part of Nature, I guess. Not always pretty, but intriguing nonetheless.