The stag beetle is one of the largest beetles in Europe. Some specimens can even grow to more than nine centimeters. The large branched jaws look exactly like the antlers of a deer that gave this beetle its name. After four to eight years, the larva pupates into an adult beetle. Once adult, the stag beetle lives only a few weeks to a maximum of two months. In the Netherlands the stag beetle is quite rare and it is a protected species.
General information
The stag beetle (Lucanus cervus) is an insect of the order of the beetles. It is one of the largest beetles found in Europe and can even reach a length of more than 9 centimeters. Height is very variable. A female is on average between 28 and 45 millimeters long and a male on average between 34 and 86 millimeters. It owes its name to the enormous jaws that are branched into a shape that resembles the antlers of a deer. Only the males have such jaws, which makes it easy to distinguish between a male and a female. The male has these jaws to impress, but he cannot bite with them. If you feel with your finger between the jaws, it can prick something with the sharp, thorn-like branches on the inside. The female’s smaller jaws are powerful and sharp. So she can bite you hard. The females have these jaws to gnaw holes in the bark of trees and then lick up the sap streams.
Reproduction
After mating, the female lays a few dozen eggs through her laying tube. The laying tube is only visible when the eggs are laid. The eggs are light yellow in color and oval to round in shape. The diameter of the egg is approximately 3 millimeters. She is able to develop eggs a second time in a season. This probably applies to only half the number of stag beetle females. The female lays the eggs against the wood in the chorus in the tunnels dug by the female in the soil. Preferably by wood that is affected by white rot or oak rot. After two to three weeks, a larva will emerge from the egg.
Larva
The larva is white with an orange head. It has 3 pairs of hardened legs and a sturdy head shield that is round in shape. Next to the mouthparts are the conspicuously present antennae. The larva is several millimeters long when it hatches. After a year the larva is a few centimeters long. The larva is highly dependent on the food supply and climate conditions for its ultimate size and lifespan. In exceptional cases, the larva can reach a length of up to 10 centimeters by eight years of age before pupating. The amount of food determines the development time of the larva. Under optimal conditions, the larva pupates after 4 years and under poor conditions only after 8 years.
Pupation
As soon as the larva has fully developed, pupation takes place. A cocoon is created that is the size of a chicken egg.
The length of the pupa stage depends on environmental factors such as temperature and humidity. It takes an average of 2 to 4 weeks for the pupa to be converted into an adult beetle (image).
Image
As mentioned earlier, adult beetles can vary considerably in size. This is related to the living conditions of the larva. The little males also have underdeveloped antlers that are not only smaller, but less branched. Once adult, the males only live a few weeks and the females no more than one to two months.
Food
The larvae eat rotting wood. They prefer to eat rotten, damp wood that has died for some time and is affected by fungi (oak rot and white rot fungi). The larva cannot live on dry wood. The beetle eats sugary foods such as plant sap from the beech and oak. The females can gnaw open the bark. This is difficult for the males because of the huge jaws. The males eat overripe fruit.
Enemies
The stag beetle is not that fast and cannot spread its wings so easily. That is why the beetle is preyed upon by many animals. If he is threatened on the ground, he will sit still. He is unable to display threatening behavior such as making wheezing or hissing noises or excreting smelly or biting bodily fluids. The beetle is preyed upon by birds, frogs and predatory mammals. The male can try to impress an enemy with the jaws, but he cannot bite off with it. The male is completely defenseless and an easy prey. The larvae are mainly predators of parasitic wasps, birds such as woodpeckers and jays. Dagger wasps deposit their eggs on the body of the larva that the stag beetle eat from the inside.
Protected species
The stag beetle is legally protected in the Netherlands and Belgium. This beetle also has a protected status in the rest of Europe. In the Netherlands, the stag beetle is included as a protected species in the Flora and Fauna Act. It is prohibited by law to catch or keep copies. There has been research into the distribution of the stag beetle in the Netherlands where it is a very rare animal. The largest distribution area of the beetle in the Netherlands is in Limburg.