ANIMAL ESTATE client 8.02: STAG BEETLE
FOR ANIMAL ESTATES 8.0: LONDON
SCIENTIFIC NAME: Lucanus cervus
RANGE: This species of stag beetle, part of the Lucanidae family, is found across most of Europe and the UK, although they are predominantly distributed around Southern and South Eastern regions of the UK and central and Southern areas of Europe. They are especially common in areas in and around the Thames valley, as well as the Severn Valley and parts of the South-West coast, north Essex, south east Suffolk, south Hampshire and West Sussex, with small populations in a few areas in Devon and Worcestershire. These distributions can be accounted for on the basis that they prefer areas which have the highest average air temperatures and the lowest rainfall levels throughout the year.
HABITAT: Stag beetle larvae feed on moist rotting wood buried underground, usually 30-60cm deep. Rather surprisingly though, forests are not the beetles primary habitat. Instead the highest concentrations are found in gardens, parks and hedgerows. The females, when finding a suitable site to lay her eggs, usually prefers oak, but when this is scarce she will seek out logs, old tree stumps, woodchip piles and even old fence posts. However rotting wood is not the only prerequisite for stag beetles. They prefer light soils as females have to dig down to bury their eggs and newly emerging adults have to find their way to the surface. As a result, areas like the North and South Downs, while having relatively stable climatic conditions, have very few stag beetles due to the chalky ground. In these areas, they occur only in ribbons along riverbanks which are often lined with old trees. Similarly, there seem to be few stag beetles in the Weald between the North and South Downs, as the Downs themselves present an almost impenetrable barrier to them.
HOME CONSTRUCTION: In June or July, when a female is ready to lay her eggs, she will usually return to the same place that she was born herself. Here she will dig down to about 30cm and lay up to 21 3mm long eggs in a moist, rotting tree bark crevice. The larva, once hatched, will remain below ground and feed on rotting wood for up to 6 years, leaving a trail of tunnels and C-shaped chambers behind it. Stag beetles begin to pupate in early autumn a year before they are to emerge as beetles. The larva will move out into the soil and construct a cocoon of earth around itself and by winter they will already have fully formed. However they will remain underground and only finally emerge in May or June the following year.
BUILDING MATERIALS: Pupation occurs within a chamber built with wood pieces, soil, gut excretions and other materials stuck together with saliva. Otherwise neither the larvae nor beetle make any other kind of construction, accept perhaps for the tunnels dug as a result of the mother seeking to lay hers eggs and the larva seeking food underground.
BUILDING MOTIVATION: Due to the length of time that the Stag Beetle exists in its venerable larval state, it is essential for it to live and feed out of site and protected from rummaging prey. As a result the eggs are laid some depth under ground and within the relatively tough outer layers of a decaying tree. Likewise the cocoon that the larvae constructs in preparation for its pupation helps protect it from predators and also from being squashed while it transforms into it adult body. Any imperfections or disturbances in the cocoon shell however will likely cause deformations in the beetles wing casing and body as its shell hardens.
MAKING A STAG BEETLE NESTING SITE: Human measures can be taken to encourage stag beetle populations by the construction of habitats and nest sites. These can as simple as buried log or woodchip piles or a woodchip filled bucket with holes in the side buried in the ground. Leaving any cut down timber on the ground at the site instead of clearing it will help to reinforce the correct habitat. Forest managers in the UK have now widely adopted this technique to try to stimulate growth in the stag beetle population.
THREATS: The main predators to stag beetles are magpies, they leave the beetle in a characteristic way, just head, thorax and wing cases, with some or all of the legs. The beetles can survive like this for up to several days. Other predators include, foxes, (they eat them whole and bits are found in the pellets) other birds, bats, hedgehogs and cats - which tend to puncture the beetle then lose interest rather than kill them. Then of course there's man - not a predator but he kills many every year by destroying the habitat, running the beetles over, and perhaps the worst of all -deliberately stamping on them!
INTERESTING FACTS:
- Stag beetles (Lucanus cervus) are Britain’s largest terrestrial beetle.
- Lucanus Cervus are so called because Pliny the Elder noted that Nigidius called the stag beetle lucanus after the Italian region of Lucania where they were used as amulets.
- Male beetles use their antlers to fight other males, resembling deer, hence the nick-name ‘Stag Beetle’.
- Adult stag beetles only live for about 6 weeks. Their only purpose is to mate and for the female to lay eggs.
- Adult stag beetles do not eat, instead they rely on the fat reserves built up as a larva. Some beetles do however drink tree sap, fruit juice or nectar.
- Stag beetles are completely harmless despite their appearance and will only bite if scared and provoked.
- Man is the biggest killer of stag beetle due to loss of habitat through forest management and overly tidy gardeners! Other accidental and deliberate actions such as the introduction of cats, running over and squashing are also factors.
- Interestingly, while the stag beetle is globally endangered, Bromley, Croydon, Richmond and Lewisham are hotspots in London for the creature.
RESOURCES:
London Wildlife Trust, Stag Beetle Project
Natural History Museum
People's Trust for Endangered Species
Entomologia: Biology of the Stag Beetle
Stag Beetle Info
Wikipedia
Stag Beetle Helpline
University of Nebraska State Museum
London Wildlife Trust
hYoung People's Trust for the Environment
Worcestershire Wildlife Trust
Maria Fremlin: Stag Beetles
Wildlife Extra
(All accessed 28.11.11)
COMPILED BY: Mark Martines