S is for Stag Beetle

“Carrying a Stag Beetle under your hat is an insurance against lightning strikes!”, taken from “Bugs Britannica” by Peter Marren and Richard Mabey

Harmless and protected under the Wildlife and Countryside Act 1981, the Stag Beetle adult (growing up to around 70mm) is an awesome sight but the larva is just as impressive, being a white grub large enough to fill a hand!

Its Latin name, Lucanus cervus, derives from Lucania in Italy (where it was named Lucanus in Roman times) and Cervus, a genus of deer – the enormous jaws of the male Stag Beetle resemble stag’s antlers, and are indeed used to fight other males and in self-defence.

Stag Beetles prefer warm, dry areas and so in the UK are found mainly, but patchily, in SE England.  They live for several years which are spent, apart from a last few summer weeks, as larvae feeding underground on decaying wood.  This is difficult to digest, so larvae rely on a specific yeast species in the gut to help break it down.  If disturbed, a larva may “stridulate” by rubbing small teeth on its mid-leg against ridges on its hind-leg.  This may be to deter predators or even to communicate with other larvae and orientate themselves to avoid competition for the rotting wood.

At the end of its life, a male will emerge from the ground and fly in search of females – it can fly for at least an hour, can cover four to six kilometres, and occasionally reach an incredible speed of 10 km/hr.  After mating the female lays her eggs in rotting wood underground.  Male and female both then die.

Sadly listed as Nationally Scarce and declining, probably due to habitat loss and disturbance, we are lucky in Suffolk to have a hotspot of their presence in and around Ipswich:

Stag beetle survey

Stag beetle survey

This map shows Stag Beetle records logged by the general public for the Suffolk Biodiversity Information Service on-line Stag Beetle Survey.  During the last 20 years 1,613 records have been logged.

You can help Stag Beetles:

Thanks to local researcher Colin Hawes who has studied Stag Beetles for over 25 years and identified several colonies in Suffolk.