The Wren Wildlife Group, London Wildlife Trust and Wild Wanstead have compiled a list of 10 species at risk of local extinction. In the fifth of a series of articles looking at each species in turn, Susie Knox is in awe of the stag beetle
As insects go, stag beetles are about as impressive as they get – easily holding their own against some of the weird and wonderful invertebrates found in tropical parts of the world. They live in woods, hedgerows, parks and gardens. Stag beetles look scary but pose no threat to humans! They’re rare to see, so if you spot one, you are very lucky.
Adult male stag beetles are 3.5–7.5cm long, with large, antler-like jaws. The females don’t have these mandibles but still grow up to 5cm in size. The males display their massive jaws to attract females and duel with their rivals. Stag beetles can live up to seven years, but they spend most of that time underground in their larval stage. Even the larvae of male stag beetles have large jaws!
When ready to mature, stag beetles build an egg-shaped cocoon in the soil, up to 20cm below ground. It can be as large as an orange and take up to three weeks to construct. Within the cocoon, the larva pupates and turns into its adult form. After spending winter and spring in the soil, adult beetles emerge above ground from mid-May onwards to mate. By the end of August, most of them will be dead. Look out for females on the ground searching for a place near rotting wood to lay their eggs. Males tend to be seen flying on the hunt for a mate.
Stag beetles have declined in Europe and are red-listed in many countries. They are protected in the UK under the Wildlife and Countryside Act and are a Priority Species under the UK Post-2010 Biodiversity Framework. Stag beetles are suffering from loss of habitat. The UK has lost much of its native broad-leaved woodland and the decaying wood they need is often removed to make things look tidy. Stag beetles are found in areas of southern England, but fewer are recorded in east London than other parts of the capital, particularly in the south and west. In Wanstead, they are rarely seen, and are less frequently encountered than their not-quite-so impressive cousins, the lesser stag beetle. The City of London is aware of the need to leave decaying wood, a key habitat for so many species, including the stag beetle. As such, stag beetle sightings are probably a good indicator of the health of many other species locally – which is why the lack of them in Wanstead is so concerning.
How to help:
- When out and about, leave old stumps and deadwood alone. Female stags lay their eggs in rotting log piles, old fence posts and the roots of various rotten trees, including oak, apple, ash and cherry.
- Build a log pyramid for stags in your garden. Find out how at wnstd.com/logpile
- If you’re mulching any of your flower beds, use untreated woodchip, which can also provide ideal habitat for females to lay their eggs in and a food supply for the larvae.
- Create an area of wild lawn. Mow once a year in late summer and remove the cuttings (this will help wild flowers naturalise).
For more information about the 10 species under threat of extinction in Wanstead, visit wnstd.com/the10