Adult chafers eat the leaves and flowers of many deciduous trees, shrubs and other plants, but rarely cause any serious damage. However, their fat, white grubs (reaching 40-45 mm long when full grown) live in the soil and feed on plant roots, especially those of grasses and cereals, and are occasional pests in pastures, nurseries, gardens, and in grassy amenity areas like golf-courses. The injury to grassland and lawns results in poorly growing patches that quickly turn brown in dry weather; the grubs can be found immediately below the surface, usually lying in a characteristic comma-like position.

The grubs sometimes attack vegetables and other garden plants, e.g. lettuce, rasberry, strawberry and young ornamental trees. Injury to the roots and rootstock causes small saplings and tender tap-rooted plants like lettuce, to wilt suddenly or to show stunted growth and a tendancy to shed leaves prematurely. Plants growing in rows are usually attacked in succession as the grubs move along from one plant to the next. Chafer grubs feed below ground for 3-4 years before changing into adult beetles.