In the adult stage, beetles appear on the surface of the earth at the end of April or May and live about 5-7 weeks. After about 2 weeks, mating occurs, after which the female begins laying eggs, placing them under the ground at a depth of 10-20 cm. This process can take place in several methods, and a total masonry is 60-80 eggs. After finishing the masonry, the female of the beetles of May dies immediately.
Eastern May beetles prefer to lay in open areas, and western beetles among trees. During this period, the beetles eat leaves of trees – mostly oak, birch or maple, but also needles of coniferous species. In some years, when the number of beetles is particularly high, they can cause serious damage to forest plantations.
The stage of the larvae that occurs after the earth takes a much longer time – 3-4 years, and in a cold climate and up to 5 years. The larvae hatch after 4-6 weeks. At first they feed on humus and the roots of herbaceous plants (for example, potatoes or sugar beets), and later the roots of trees.
During development, the larvae constantly increase in size, reaching 4-5 cm at the end. Vertical seasonal migration is characteristic of larvae of beetles: in a warm season they rise closer to the surface of the earth, and in winter they descend to a depth. Pupa is formed in early autumn, and after about 6 weeks, adult beetles appear, which until the end of April remain under the ground at a depth of 20-100 cm.
