Stag beetle - Terry Whittaker
Stag beetle
Stag beetles are increasingly under pressure from the loss of dead and decaying wood habitat meaning that private gardens and community green spaces are becoming even more important as safe havens. Although still familiar in the south of Suffolk the stag beetle is now a priority Biodiversity Action Plan species and it’s feared the beetle may soon become extinct at the edge of its range, such as in the West Midlands and the West Country.
Male stag beetle by Steve Aylward
Female stag beetle by Sherie New
Stag beetle larvae at Newbourne Springs, Joe Underwood
By targeting the stag beetle as an important inhabitant or visitor to your garden you can help halt its decline while attracting other insects and wildlife into your outside space.
Sightings and life cycle
The male stag beetle, which can be up to 75mm long, is easily identified by his huge jaws that resemble the antlers that give his name. The females are smaller and do not have the ‘antler-like’ mandibles. Both sexes have a shiny black head and thorax, while wing cases are a chestnut brown.
You are most likely to see a male in flight on warm summer evenings between May and August, while it is searching for a mate. The female lays her eggs in decaying wood and the larvae that develop are large white grubs with orange heads that can be found in rotting wood at, or below, ground level.
It can take 3-7 years for the stag beetle's larvae to develop into adults. They live as adults for only a few months in the summer in order to mate.
Habitat
Tree stumps
The natural habitat for stag beetles is a tree stump left in situ, so avoid stump grinding where possible.
Log piles
Creating a logpile can provide stag beetle habitat. A log pile can either be a stack of logs laid horizontally or else upright logs which are partially buried. Partially burying logs in the soil is preferable because it will retain more moisture and increase the number of visiting insects.
Create a stag beetle-friendly log pile
Here is a simple guide to creating a stag beetle-friendly log pile in your garden:
- Wood from broadleaved (not coniferous) trees, especially oak and beech will support the richest communities of invertebrates.
- Place logs in partial shade to prevent them drying out. Allow plants to grow over them to create shade and humidity.
- Fresh logs with bark attached generally provide habitats for the longest period of time and so create a wider range of habitats.
- The larger the diameter of the logs the better – they should at least be the thickness of an adult’s arm.
- If the logs are laid horizontally don’t pile logs too high as the timber on the top will dry out.
- Try and avoid areas already rich in wildlife as decomposition will add nutrients to the flower-rich sward, so encouraging rank growth.
- Log piles should not be located next to water courses and not stacked up against tree trunks or hedges.
- Avoid mowing close to log piles between May and August when adult stag beetles will be emerging.
Recording stag beetles in your garden
If you find stag beetles or larvae please record your find with Suffolk Biodiversity Information Service