About Stag Beetles - Stag Beetle Information & Facts

Stag Beetles are an important part in parks and gardens all around the UK, mainly South East England. They can be recognised by their shiny black head and thorax and chestnut brown wing cases.

Easily the most known feature, these male stag beetles appear to have large antler like jaws. These are actually large mandibles, used for fighting other males and in courtship displays. The male Stag Beetle has larger mandibles than the female Stag Beetles. Male Stag Beetles measure about 35-37 mm in length.

On summer evenings, you'll often seed adult Stag Beetles flying around searching for mates, whilst a female stag beetle will be on the ground finding the perfect spot of rotting wood to lay her eggs.

Are Stag Beetles Endangered?

No, not yet, but they are a priority species on the UK biodiversity action plan. This means that because of recent declines in Stag Beetle populations has meant that conservation efforts have been put in place.

The main reason for this drop in populations is due to the loss of habitats - particularly the removal of decaying wood.

Stag Beetles are now having habitats protected, the retention of dead wood is being encouraged and awareness of the importance of these creatures is being raised. They are also protected under the Wildlife and Countryside Act 1981 and you are encouraged to report all stag beetle sightings.

The Importance of Stag Beetles

Stag Beetle Larva work tirelessly as decomposers in the ecosystem. In the time that Stag Beetle Larvae are around, they feed on decaying wood and break it down so that it is recycled back into the soil. This is vital for plant and soil health.

In ecosystems, the presence of these Stag Beetles, including the Lesser Stag Beetle, indicates a healthy, biodiverse environment. A decline in the population of lesser Stag Beetles and normal ones can show that there is something wrong.

Stag Beetles are a part of the food chain and are a food source for various birds and small mammals.

Lifespan & Stag Beetle's Life Cycle

The life of an adult stag beetle is only short, and they actually spend most of their life in the Larval stage.

As larvae, Stag Beetles can spend 3-7 years feeding on decaying wood and growing before they move onto the pupal stage. Once ready, they will undergo metamorphosis, this can take a few months and is typically late summer to early spring.

Once ready to emerge in May, the adult is ready for the breeding season; but they only live a few months once they turn to adults and their main priority is reproduction.

What Do Stag Beetles Eat?

As adults, eating isn't the most important thing to these insects and some don't eat at all. When they do, they don't consume solid food so tree sap, fruit juices and other sugary substances are their main source of energy.

As Larvae, decaying wood is their only source of food and they burrow in it and consume it over several years.

Breeding Season

The Breeding Season begins late May to August. Males are known to dramatically fight off rival males with their mandibles to get the female's attention.

The males fly around on warm summer evenings in search of female adult beetles. During this time, and after mating, the female has to find a suitable habitat to lay her eggs; this can be in tree stumps or anywhere with dead wood for the larvae to consume once hatched.

Predators

Stag beetles, including both males with their distinctive antler-like jaws and females, face various natural predators throughout their life cycle. Adult stag beetles are vulnerable to birds such as robins and magpies, as well as small mammals like hedgehogs.

Their impressive mandibles, which are used in battles with rival males, do not provide much protection against these predators. The larvae, which develop in decaying wood, are also at risk from predatory beetles and insects that prey on them.

Additionally, the presence of predatory ants and mites in rotting wood can impact larval survival. Understanding these predation pressures is crucial for effective stag beetle conservation efforts, particularly in urban areas where their populations are already threatened.

Five Facts about Stag Beetles

1. Male Stag Beetles have large, antler-like jaws that can be up to 7.5 cm long. These “antlers” are used in battles with other males to compete for mates and territory.

2. Stag Beetles have been around for millions of years. Fossil records show that they were present during the time of the dinosaurs, making them a living link to ancient ecosystems.

3. Adult Stag Beetles have a relatively short lifespan of about 6 to 12 months. Most of their life is spent in the larval stage, which can last up to 7 years.

4. Stag Beetles are typically found in deciduous woodlands, parks, and gardens with rotting wood. Their larvae feed on decaying wood, which helps in the decomposition process and nutrient recycling.

5. In the UK, Stag Beetles are considered a protected species. Their numbers have been declining due to habitat loss and changes in land use, so there are conservation efforts in place to help protect their habitats and promote their survival.