Stag Beetle (Lucanus cervus)

	Stag Beetles: females have smaller mandibles than the males

The New Forest is a stronghold for the nationally scarce Stag Beetle, although these impressively large creatures are unlikely to be encountered during a day-time walk. Stag Beetles are, however, quite often seen around the towns and villages on warm, early to mid-summer evenings.

Elsewhere in Britain, Stag Beetle numbers have substantially reduced, partially, it’s thought, because the rotting wood on which they depend is no longer so readily available in our ever-tidier gardens and countryside. Indeed, Stag Beetle distribution is now largely restricted to the south of England, and even then is further limited to South Hampshire, West Sussex; North Essex and the Thames Valley.
 
But in the New Forest, Stag Beetles remain relatively abundant, living out their early lives in the open, unenclosed woodlands where broad-leaved trees are left to live their natural span before eventually decaying, dying and returning to the soil.

Stag Beetles are fairly easy to recognise.

Male Stag Beetles have a shiny black head and thorax – the bit behind the head - and reddish-brown wing cases. They measure between 3.5 and 7.5 centimetres (almost 1 ½ - 3 inches), including their implausibly large mandibles that account for almost half their length.

Somewhat fancifully likened to the antlers of red deer stags, the mandibles are used in battles between rivals and during courtship posturing. Thankfully, however, they are not used to bite humans.

	Stag beetle female

Female Stag Beetles are not quite so big, have darker overall colouration, significantly smaller, but much sharper mandibles, and are more inclined to bite – it’s never wise to pick one up!

Warm weather from mid-May onwards encourages Stag Beetle emergence, the time when adult males take to the wing in search of the slightly later-emerging females. Both feed on tree sap, which is lapped up with their long, yellow tongues.

Battles between rival male Stag Beetles are frequent, and it’s then that the antlers come into play, used as fearsome weapons as each tries to defeat the other. These fights, however, like those of their namesakes, the red deer, are most often trials of strength that infrequently result in serious injury.

After mating, female Stag Beetles lay their eggs in rotting wood – log piles, tree trunks and fence posts are favourite sites. Few, if any, adults survive much beyond the end of August.

During the three to five year larval stage, Stag Beetles live in, and feed on, the rotting wood. Strange-looking creatures, larvae are plump, bulbous, wrinkly, creamy-white, six-legged beasts with orangey-brown heads and jaws designed for tearing and chewing.

When ready to pupate, Stag Beetle larvae leave their wooden home and move underground, forming around themselves for protection an often sizeable cocoon. Adult Stag Beetles emerge from the cocoons in autumn, but remain underground until ready to fly in the following spring.

References:
The Great Stag Hunt: http://www.ptes.org/index.php?page=210
Collins Guide to the Insects of Britain and Western Europe: Michael Chinery
Insects of Britain and Europe: J. Zahradnik and M. Chvala