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Join the Stag Party

Stag 3
The park at Rookery Gardens is growing darker, descending into the sodium light tinged monochrome of the urban night. Around me the bats wheel, chasing one another and unfortunate moths through the backlit sky before vanishing again into the gloom of blackening canopies. No sign yet of my reason for coming here. Then one appears, emerging like the bats from the shade of the canopy, though with none of the speed and arial grace. Hanging suspended from madly vibrating wings, its absurdly oversized jaws thrust determinedly forward in stubborn defiance of gravity, the stag beetle wends its stiff journey through the air. Its legs jut out stiffly in all directions as it navigates broad turns above me, sometimes dropping so I can hear the low, desperate buzz of its membranous wings, sometimes climbing out of earshot towards the canopy. It vanishes into the darkness of a tree and is gone.

I walk lengths of the park for an hour as the darkness deepens, passers by looking ever more askance at me, shining my torch aimlessly into the darkness above. I am rewarded with more sightings of the drifting beetles, but none touch down. As I call it a night and return to my car, I hear a rustling in the grass. Shining a light on it I see the grass is crawling with stags, a dozen or more beetles of all sizes in desperate competition for the two females who, without the ability to emote, still manage to convey an air of wanting to be anywhere else. They cannot of course, this is reason they adopted this above ground final form. The beetles have come together to breed. The males use their antlers to grasp one another, lifting competitors into the air, attempting to prise them from the backs of females or turning rivals over in unintentional body slams like tiny wrestlers. The winners of this competition will mate with the females, who will lay their eggs close to or within the same piece of dead wood that she herself emerged from. The cycle begins again, in the same place.

Two nights later, the temperature hovering on the cusp of feasibility for beetle activity, I return to the site. A few beetles are still present, though the lower temperatures give what competition for mates there is a slow, desperate air. Scattered around the wrestling ring are pieces of beetle, severed mandibles and shattered heads, hollowed thoraxes and tattered wings. None of the beetles will survive the season, all will die after the breeding furore. These remains though are evidence of predation, of opportunistic killers. A number of species will take advantage of these big, energy rich insects, with urban foxes, magpies and domestic cats chief among their nemeses. Even knowing that the battle in the grass was their last hurrah, it is a sad sight to find pieces of this ever-rarer species scattered among the grass.

Stag beetles are locally common here. As a South-Wester they are not a creature I’m used to seeing, restricted as they now largely are to the south east of England. They live a secretive life, almost entirely subterranean as a fat white grub. This part of their life cycle lasts between three and seven years, largely dependent on weather conditions during this time, and is spent gorging on dead wood up to half a metre below ground. Once they are at their full size, they depart their dead tree nursery and burrow into the soil, where they build a large cocoon in which to metamorphose into their final, familiar form. After pushing their way to the surface, the adults are almost solely focussed on finding a mate, to the extent that they almost entirely neglect to eat. Relying on fat reserves and topping up energetically using sap runs on trees, the beetles take to the air. Females are more sedate, often choosing to walk or stay put altogether, with the males homing in on them on the wing.

Stag beetles are a victim of our tidiness. The life cycle outlined above is dependent on the presence of a continual supply of dead wood, both above and below ground. In our age of aesthetic and safety, the remains of trees are often completely removed from the landscape, often up to and including the root plate via stump grinding. Without a steady supply of these features, populations of stag beetle will find it difficult or impossible to persist. This is why it is important to leave trees where they fall or, even better, allow part of them to remain standing after they die. It is also important to allow trees of a variety of ages to persist in known stag beetle sites. If the root plates of ancient trees are used up and no more are available, stag beetle populations can become very vulnerable. We must also ensure we do not demonise those animals that predate the beetles. Insect aggregations of this kind always result in a high predation rate, but the impact of cats should be noted.

Appropriate management of our parks and woodlands can ensure a thriving community of this, Britain’s largest insect, well into the future. You can also help in your garden, by leaving the stumps of trees in place when they are felled, or by creating a stag beetle pyramid from natural wood logs. See the People’s Trust for Endangered Species website for more information. Remember, stags pose no threat to people or to living trees so make the most of any encounter you have with them. They might look scary, but it is a privilege to spend time with them.

Written by Phil Bruss