Spring phenology of cockchafers, Melolontha spp. (Coleoptera: Scarabaeidae), in forests of south-western Germany: results of a 3-year survey on adult emergence, swarming flights, and oogenesis from 2009 to 2011

Abstract

Cockchafers are among the most dreaded insect pests in many European countries, causing economic losses in agriculture, horticulture and forestry. In forests of south-western Germany, populations of the forest cockchafer (Melolontha hippocastani) and also the field cockchafer (M. melolontha) have been increasing during the past three decades and, therefore, monitoring of these populations has been intensified. In the present field study, data on adult emergence from the soil, male swarming flights and female oogenesis, collected at three infestation sites by visual inspection, with soil eclectors and with light traps in early spring 2009-2011, are presented and discussed in the context of the current knowledge of cockchafer biology. Furthermore, three air temperature sum models for the prediction of the onset of the swarming flight period in spring, published in the early/mid 20th century, were validated in view of their applicability in forestry practice.