Spectacular stag beetles can reach sizes of 75mm. Sadly their numbers are declining across Europe and they are now extinct in some countries. In the southern parts of the UK they are doing much better but they need our help if they are to hang on.
Adult stag beetles are often seen flying around on warm summer evenings or their large white larvae (grubs) are dug up by gardeners.
Stag beetle facts
- Stag beetles are big – up to 75mm long. Only one UK beetle is bigger and that’s a water beetle.
- The larvae live in rotting wood for several years before they make a cocoon and transform (pupate) into adult beetles.
- Stag beetles emerge in summer and live just a few weeks while they search for a mate.
- Adult beetles don’t eat – instead they live on the fat they stored while developing as larva.
- The male’s antler-like jaws are used to fight off rival males.
Why are stag beetles threatened?
Stag beetles are threatened by habitat loss. The larvae (grubs) can live for several years underground and need plenty of rotting wood to eat throughout this time. By tidying parks, woodland and gardens and removing tree stumps, we reduce the amount of deadwood and therefore the larvae have nowhere to live and nothing to eat.
When stag beetles emerge as adults, they live only a few weeks while they search for a mate. During this time adult stag beetles face ricks from humans, cars, cats and magpies.
Frequently Asked Questions
I have found an adult stag beetle – what do I do now?
Enjoy observing such a magnificent beetle. Leave it where it is (unless it is in immediate danger of being run over or trodden on) and then record your sighting. If you do have to move a stag beetle for its own safety, then please move it as short a distance as possible (into a nearby hedge or plant for example).
What do I do if I dig up a stag beetle larva?
Larvae (or grubs) live underground feeding on rotting wood. If you can, put it back exactly where you found it. Or the next best thing is to re-bury the larva in a safe shady place in your garden with as much of the original rotting wood as possible.
The easiest way to tell apart beetle larvae is where you find them. Stag beetle larvae are found in decaying wood underground, lesser stag larvae are found in decaying wood above ground, cockchafer larvae are found in soil feeding on living roots and rose chafers are usually found in compost heaps. Please see our larvae ID guide for photos and further details.
How can you tell the difference between a male and a female stag beetle?
Males have the characteristic large antlers (mandibles) which can be the same size as their body (sometimes bigger) whereas females are smaller and have smaller mandibles. For more information please see our stag beetle fact file.
I have found larvae in my compost heap what should I do?
Any larvae found in a compost heap will usually be rose chafers, as stag beetles tend to live underground in rotting wood. You can leave the larvae where they are as they are beneficial composters.
Will a stag beetle bite me?
If you hold a stag beetle it is possible (though unlikely) that it will bite you. To avoid this please wear gloves if you have to handle a stag beetle or even better don’t try to hold it. They are not poisonous and will leave you alone if you leave them alone.
How can I make my garden suitable for stag beetles?
Stag beetles need decaying wood that is underneath the soil. Your garden may already be ideal for stag beetles with plenty of rotting wood (even wood chip and old fence posts can provide homes for stag beetles!) If not you could make a log pile.
There are stag beetles on an area of land I know is going to be developed – what can I do?
The stag beetle is a species of conservation concern. Its presence will not stop a development but there must be a reasonable survey and mitigation measures put in place if development goes ahead. For more tips on opposing a development please visit ptes.org/planning-development-biodiversity
For other stag beetle questions please email firstname.lastname@example.org.
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