Beetle larvae are better known as grubs and can cause a lot of damage in turfs and lawns. The garden chafer (Phyllopertha horticola) is the most commonly occurring species.
In summertime, grubs feeds on roots and soon it will be obvious that parts of the lawn does not grow well and start to change into a less fresh and yellow-brown color. It is not uncommon that with a heavy infestation, turf and lawns can be so badly damaged that they come loose from the earth and it may even be possible to roll them up. Under the divot a mass of grubs, sometimes up to 100, may be present. When turf and lawns endures a drought period, the affected and damaged areas can be completely scorched and die. In addition, the presence of grubs will attract moles and birds, leading to secondary damages.
Adult garden chafers are 8-12 mm long and have red-brown slightly hairy wings with a dark edge. The neck shield is metallic green to shiny black. They appear in late spring and early summer. During the first night that the adults are active, mating takes place. Immediately after, females crawl into the ground to deposit around 85% of their eggs and fly out the next morning. Low flights just above the soil surface are very characteristic for the garden chafer. For a period of 3 weeks the adults will feed on buds and leaves and soon after follows a second session of egg laying. The first grubs appear after 3 to 6 weeks and immediately begin to feed until mid-autumn. The grubs have a brown head and a beige-white body. The life span of the larval stages is 1 year. As soon as the temperature begins to drop in autumn, most of the larvae move deeper in the soil to hibernate. If the temperature increases in spring, the white grubs pupate in early spring and from late spring they reappear as adult garden chafers.