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When most people think of stags in Richmond Park they imagine the male red deer, all antlers and bellowing on misty autumn mornings. They don't realise that the park is also home to another type of stag, the endangered and distinctive Stag Beetle.

The Stag Beetle is a gentle giant of the insect world. Despite a reputation for summoning thunder and lightning, the male Stag Beetle is entirely harmless. They may look scary to some people but their large jaws are only used to wrestle with other males and their bite is too weak to hurt you.

Stag Beetles have a long life cycle of up to seven years.

With greatly reduced numbers across the UK and a European wide protection programme, the presence of Stag Beetles was instrumental in Richmond Park's designation as a National Nature Reserve. Stag Beetles can be encouraged in every garden, but adopting this crusty coleopteran will help us protect these nationally important colonies.

About the Stag Beetle

The Stag Beetle is an amazing creature but it's still not fully understood even by experts. For example, although we know they have a life cycle of up to seven years, we aren't really all that sure what they eat once they've transformed from larvae into adults. Some studies indicate they might feed on tree sap, others that they just don't eat full stop. Perhaps both are true, depending on the individual beetle.

The Stag Beetle is Britain's largest terrestrial beetle, with males growing to 7cm and females to 5cm. The males have large mandibles that look a little like the antlers of a deer, hence its common name. Females don't have such big mouth parts. The antlers are used for territorial fighting between males; they try to grab each other and then throw the opponent. In theory both males and females could nip you and draw blood but this rarely occurs and they're not at all dangerous.

Stag Beetles need old, established woodland. As larvae they feed on rotting tree matter. They used to be found all over Europe but, because of the gradual loss of woodland, they are now extinct in some countries, such as Denmark. The Stag Beetle is considered to be globally threatened and is listed as a priority species in the UK Biodiversity Action Plan. It is a protected species through its listing in Schedule 5 of the Wildlife and Countryside Act 1981 (as amended).

The lifecycle of the Stag Beetle starts with the females laying their fertilised eggs, which are about 2-3mm in diameter, in damp earth, near rotting wood (it seems favoured species are Oak, Ash and Elm). The eggs hatch into larvae, which develop below ground in decaying tree stumps or partially buried deadwood and feed on the rotting wood over a period of up to five years. The larvae pupate in the autumn and emerge the following spring; mating occurs in June and July and the females lay their eggs in the autumn.

Threats to Stag Beetles

Stag beetles face a range of threats.

The most obvious problem for stag beetles is a significant loss of habitat. Many woodlands were sold for development in the inter-War years; just think of all the suburbs built since the 1920's. The introduction of the Green Belt in 1947 did restrict suburban expansion but since then many of London's surviving open spaces have sadly been developed, including many woodlands. Development will continue to reduce stag beetle habitats, but increased awareness of their existence can help defend the Beetles against developers.

In addition to the loss of habitat, the removal of wood from woodland is also a problem. In previous decades dead or rotting wood, which is the stag beetle's food source, would have been tidied away. Although some tidying up still continues in woodlands and parks, managers are now much more aware of the need to retain dead wood as part of the woodland ecosystem. Our management plans for Richmond Park, and other Royal Parks, include the retention of suitable dead wood to help encourage stag beetles to settle.

Changes in weather patterns also have an impact on our Lucanidae friends. Recent long dry summers seem to have resulted in more and more predators digging up and eating eggs or larvae. Predators such as cats, foxes, crows, kestrels and others may also have an adverse impact at the most vulnerable stage in the beetle's life cycle, when adults are seeking to mate and lay eggs. Though this is largely natural predation, it has been suggested that the rise in the numbers of magpies and carrion crows in the last decade may be having a significant impact on Stag Beetle populations.

Humans are, unfortunately, a direct threat to the stag beetle. Adult beetles are attracted to the warm surfaces of tarmac and pavements, making them particularly vulnerable to being crushed by traffic or feet. Stag beetles have a fearsome appearance and sometimes people kill them because they look 'dangerous'. We need more volunteers to help with research so that we can further understand these intriguing insects.

The good news is that stag beetle protection is one of the priorities of the UK Biodiversity Action Plan. Organisations like us are working hard with other groups to preserve the environment and habitats that the beetles need, so with your support we can help ensure the future will turn out well for these 'gentle giants'.

Fun facts about the Stag Beetle

A few Stag Beetle facts you might not know...

  • The Stag Beetle is Britain's largest native ground-dwelling beetle. Adult females can be up to 5cm long and some males may reach 7cm - that's bigger than a fun-sized choccie bar.
  • Believe it or not Stag Beetles can fly. Males will fly out to look for a mate at dusk on humid, thundery evenings between May and August.
  • Female Stag Beetles can also fly but rarely do so. Instead they release pheromones (a special set of chemicals, a little like a sexy perfume) to attract males to them.
  • Stag Beetle larvae are really good for your garden. They eat loads of rotting wood, returning important minerals to the soil, but don't eat living plants or shrubs.
  • Male Stag Beetles have large mandibles (jaws) that look a bit like the antlers of a deer, hence its name. Females don't have such 'big mouths' but their jaws are actually much stronger.
  • Male Stag Beetles use their antlers to wrestle other males during the mating season. They try to grab each other and the winner throws the loser to the ground.
  • Stag Beetles were also called billywitches, oak-ox, thunder-beetle and horse pincher - you can imagine what sort of stories went along with those names!
  • Classical Greek myth claimed that a famous musician named Cerambus, who played the lyre (a kind of U-shaped harp that looked a little like a Stag Beetle's antlers), was rude to some nymphs and they turned him into a Stag Beetle as punishment.
  • According to British folklore, Stag Beetles summoned thunder and lightning storms, which scared the wits out of medieval peasants who also believed that they flew around with hot coals in their jaws setting fire to buildings.
  • In Germany the Stag Beetle was associated with Thor, God of Thunder and there was a myth that if you placed a stag beetle on your head, it would protect you from being struck by lightening... do not try this at home... or anywhere else...
  • Most Stag Beetles live for only a few weeks after emerging as an adult, with many dying during the winter. A few can survive if they find somewhere nice and warm to live, like a compost heap.
  • Stag Beetles have a long life cycle, lasting up to seven years from egg to adult. You can compare this to the maximum lifespan of other living things below (though not all of them live in Richmond Park):
Mayfly 10 days
Worker Ant 1/2 year
Worker Bee 1 year
Mouse 4 years
Guppy 5 years
Stag Beetle 7 years
Chicken 15 years
Camel 50 years
Galapagos Tortoise 193 years
Oak Tree 1000+ years

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