Adult cockchafers feed on the edges of forest plantations, getting as far as 50 m inside the woods. They prefer leaves of oak, beech, maple, elm, hazel, poplar, willow, as well as fruit trees. With a density of 5 to 40 beetles per square meter, plant damage may reach 25%.
Cockchafer larvae can be serious pests of cereals, grasses, and vegetables, as they live in the soil feeding on roots. They also attack various plants in gardens, nurseries, and pastures.