Common Stag Beetle Fact File
Stag beetles are named for the large mandibles of males which resemble the antlers of a deer. These are used during combat with other males. Females have smaller mandibles and are smaller overall.
Their body is black across the head and thorax with a chestnut-brown abdomen. This abdomen is a cover for the wings which rest underneath. The mandible of the male may be brown, black or pinkish-red.
Protruding from the top of the head are a pair of antennae which have a feathered appearance at the ends.
As an insect they have six legs which end with a small hook for clinging on to items in their habitat and a hard outer shell to protect their body.
Males may grow as large as 7.5cm (3in) long while the smaller females averages 3-5cm (1.2-2in).
Adults may not feed instead living off the energy reserves which they have from their larval stage. Most of their efforts as a male are focused on mating. If adults do feed it is on tree sap or the juices of decaying fruit. The large size of the mandible may prevent males from eating.
Larvae will feed on decaying wood.
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Europe and Asia is the home of the stag beetle. Here they can be found in the following countries – Albania; Andorra; Austria; Belarus; Belgium; Bosnia and Herzegovina; Bulgaria; Croatia; Czechia; Estonia; France ; Germany; Greece; Hungary; Italy; Latvia; Lithuania; Luxembourg; Moldova; Montenegro; Netherlands; Poland; Portugal; Romania; Russia; Serbia; Slovakia; Slovenia; Spain; Sweden; Switzerland; Turkey; Ukraine and the United Kingdom.
This species was previously present in Denmark but it is now though to be extinct there.
They make their home in oak forests and other forest type depending on where they are found.
Larvae develop in decaying wood with this decay always caused by white-rot fungi in the trees they inhabit. Naturally they use tree stumps but in human inhabited areas they may develop in decaying fence posts.
The males will complete their pupation between May and June a couple of weeks before the females so they can establish their territory.
Males use the antler like mandible in battles for mating rights with the females. They will lock their horns together and attempt to flip their opponent over.
Females will move through the territories of multiple males and mate with them.
Following a successful mating the female will find a decaying tree stump or root where they can lay up to 20 eggs. Some return to the spot where they were born to lay their eggs.
At hatching the young is a larvae which has a long white body with an orange head. These live in the rooting wood which they eat and generate a food reserve which they will use as an adult.
They spend between five and six years in the stage before metamorphosing in to the adult form. During this time they will shed their exoskeleton up to five times. Once they take on the adult form they only live for around 3 months.
To pupate they will form a cocoon from chewed wood fibers which may be as large as an orange. Inside this chamber their larval body is broken down and converted to the adult form.
The common stag beetle is a frequent flyer. Males take flight more often travelling around their territory to patrol it.
Predators and Threats
The jaw is quite weak and cannot harm humans.
Humans affect their population be removing rotting wood which they require to develop. They are also under threat from increasing urbanization.
Some small levels of collection for the pet trade also occur.
In the middle east they are viewed as a pest as they dig in to the roots of date palms.
The common stag beetle is the largest beetle in the United Kingdom.
In folklore the common stag beetle was thought to bring thunder and lightning.
By J.F. Gaffard Jeffdelonge at fr.wikipedia – photo by Jeffdelonge, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1666093
By Stu's Images, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=36442229
By Andrew Butko, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1265988
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By Q-bit array – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=50693083
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By Bugman95 – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=28174042
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