Despite it being such a large and spectacular insect, surprisingly little is known about the habits of the stag beetle. In 1998 the People's Trust for Endangered Species (PTES) invited the public to look for the beetles, asking questions about where they were finding them, the type of wood it was found near, was it eating and so-on. The 'Stag Hunt' revealed that the beetles lay their eggs both in rotting log piles and in the roots of an assortment of rotten trees, including oak, apple, ash and cherry. They seem to have a preference for oak, especially those growing along riverbanks. They also prefer warm places on sandy or light soils, and are now mostly reported from urban and suburban gardens. In fact, seventy percent of the beetles reported were found in gardens.
The larvae of the stag beetle live within their rotting logs for up to four years before pupating and emerging as adults at the beginning of the flight season the following year. However, the adults have a much shorter life than the larvae, and only survive for a few months. It used to be thought that adult stag beetles died at the end of the year but, as a result of the survey, it seems some beetles can survive the winter. The main message from the survey was, sadly, that the beetle seems to have declined in numbers greatly, especially in some areas.