Lucanus cervus

Stag beetle
92/43/EEC Directive ann. II

It is the largest beetle in Europe(up to 8 cm).
The male has huge mandibles that resemble deer horns, used only during fights between males for possession of the females that are smaller (with small jaws).
The stag beetle lives in the mature hardwoods, especially oak forests with decaying wood. The females lay their eggs in tree stumps or into cavities of old trunks.
The larva is white and has a robust mouthparts, it feeds on decaying wood and is able to digest cellulose with special colonies of bacteria hosted in the gut.
The larvae development is slow and can last from 4 to 6 years, while adults live only a couple of months.
It is served by Regional Law 9/2007 as a species of regional interest, its capture and killing  is forbidden. The stag beetle is in decline throughout all Europe due to the mature oak forests reduction, the large trees depletion and the excessive cleaning of dead wood from the forests.