Melolontha melolontha

The common cockchafer (Melolontha melolontha), also colloquially known as the Maybug, Maybeetle, or doodlebug, is a species of scarab beetle belonging to the genus Melolontha. It is native to Europe, and it is one of several closely-related and morphologically similar species of Melolontha called cockchafers, alongside Melolontha hippocastani (the forest cockchafer). The cockchafer develops via metamorphosis, in which the beetle undergoes stages of eggs, larvae, pupae and adults. The mating behaviour is controlled by pheromones. The males usually swarm during the mating season while the females stay put and feed on leaves. The leaves release green leaf volatiles when they are fed on by females, which the male can sense and thus locate the female for mating opportunity. The larvae use both the plant volatiles and CO2 to locate the plant root for food. This species is an important and nutritious food source for many species. The adults and larvae feed on plants, and are regarded as agricultural pests of crops such as grasses and fruit trees. Adults have harmful effects for the crop when they aggregate in large groups. The larvae can cause severe damage and kill the plant by gnawing the plant roots.

from Wikipedia