May beetles are a genus of beetles. There are different types: The field cockchafer is the most common in Central Europe. The cockchafer is found in the north and east and only in a few areas of Germany. The Caucasian cockchafer has become very rare in Central Europe. You can only find it now and then in the southwest of Germany.
Cockchafers are about two to three centimeters long. The outer wings have four ribs running lengthwise. The males have much larger antennae with seven lobes. The females have only six lobes on the antennae. You almost need a magnifying glass to see this. The expert recognizes the different types at the end of the rear part.
The different species look very similar and live similarly. Because of this, and because we almost only see the cockchafer, it is described in more detail in this article. Because he is almost the only one, he is usually simply called “Maybeetle”.
How do cockchafers live?
May beetle develop in a circle, similar to butterflies or frogs. We see cockchafers in spring, in the month of May. Hence they got their name. They mainly eat leaves from deciduous trees. After mating, the male dies. The female burrows about eight inches into soft soil and lays a little over twenty eggs there. Each is about two to three millimeters long and white. Then the female dies too.
Larvae hatch from the eggs after about four to six weeks. They are called grubs. They eat the roots of various plants. This includes not only grasses, herbs, and trees, but also potatoes, strawberries, carrots, lettuce, and other crops. The grubs are therefore among the pests of farmers and gardeners. In the second year, they eat a lot.
The grubs molt three times because the skin doesn’t grow with them. In the third year, they pupate and in the fall they become real cockchafers. However, they spend the following winter underground. They do not burrow to the surface until their fourth year. Their life as an “adult” cockchafer lasts only four to six weeks.
In the south, cockchafers only need three years for the whole development. What is special is that cockchafers “align themselves”. There is a lot in a year. This is called a cockchafer year or a flight year. May beetles are rare in the years in between. Every thirty to 45 years there is a veritable plague of cockchafers. Scientists haven’t yet figured out exactly how this happens.
Are cockchafers threatened?
Cockchafers are a popular food: Many birds like to eat cockchafers, especially crows. But bats also hunt cockchafers. Hedgehogs, shrews, and wild boars like to dig for grubs.
We used to have a lot of cockchafers. Almost a hundred years ago, cockchafers were collected. The communities bought the dead animals from the collectors so that the plague could be controlled. Later they were fought with poison to protect agriculture. Today there are hardly any real cockchafer plagues. They are always about the same number.