Larvae of the cockchafer; the most common species in Central Europe is the field cockchafer (Melolontha melolontha). This last appeared in large numbers in the 1950s. From the end of the 1990s onwards, there were again massive occurrences in Switzerland, South Tyrol and in the German Kraichgau (wine-growing region of Baden), which required control measures. The field cockchafer generally undergoes a three-year development and flies every fourth year. In the first year, after mating from late April to early June, eggs are laid at a depth of 10 to 25 centimetres. After about six weeks, the three-stage larvae (grubs) hatch and feed on the roots of vines until autumn.
After hibernation, the larvae continue to feed on the roots in the second and third year. In September of the third year, the sexually mature beetles hatch, overwinter and then fly in the fourth year. The beetles themselves feed on various deciduous trees, but the vine is not a preferred food. The grubs can cause considerable root damage, especially in nurseries and young vineyards. Control is carried out in the year of flight by covering the soil with close-meshed nets to prevent emigration, and with biological agents (fungal pathogens) or insecticides. See also under vine enemies.
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Markus J. Eser
Weinakademiker und Herausgeber „Der Weinkalender“