Sometimes they congregate in such numbers that they completely defoliate isolated trees. They return to the soil just before dawn. Eggs are deposited in the soil at a depth of l to several inches. They apparently are deposited most abundantly in sod that has not been disturbed for years, although they occur in almost any type of soil porous enough to permit the female beetles to crawl into it. Eggs hatch in 3 or 4 weeks.
Tiny larvae feed largely on vegetable matter in the soil during the remainder of the first season.
When cold weather appears, most species of white grubs burrow down below the frost line and remain there until the following spring. Grubs spend all of the next summer feeding on the roots of plants. During the second winter, they continue as larvae below the frost line in the soil. In the third year, they return to the plant roots and feed until late June or July, when they change to pupae in small earthen cells. The adults emerge from the pupal cases a few weeks later but remain in the soil until spring.