The next stage: pupation
After around five years as a larva, the beetle then undergoes a dramatic transformation. To begin, the larva will move out the wood for the final time and into the soil. Its skin will take on a brittle, papery appearance and the larva will begin to construct a large cocoon of earth around itself. Inside this cocoon a whole series of changes will occur as the larva becomes a pupa.
This is the pupa of a male stag beetle. As you can see, at this stage the sex of the beetle is immediately obvious for the first time with the characteristic antler-like mandibles clearly visible. The female pupa looks much the same simply without the large mandibles.
Stag beetles pupate in early autumn of the year before they emerge as beetles. However, they only remain as pupae for a few weeks. Over the course of these weeks, the outline of a fully developed beetled gradually begins to appear beneath the skin. Eventually, the pupal case will split and the beetle will crawl free.
However, this is not the end of the transformation. When it first emerges from its pupal case, the beetle is much lighter in colour than it will be when it finally emerges and the wings are fully extended. It takes around 24 hours for the beetle to fully darken in colour and for it to dry out and fold up its wings.
By the time the winter comes, the beetle will be fully developed. However, it does not emerge yet. Instead, it remains underground for the entire winter and much of the spring, finally emerging in May to June of the following year…
Go on to the next stage…