beetles

Otiorhynchus sulcatus (vine weevil or Cockchafers)

characteristics: Adult beetles are 7-10 mm wide, brownish black in color with pale yellow spots on their backs, they cannot fly.

Adult beetles are mostly nocturnal, hiding by day. Adult beetles feed on the leaf margins. The beetles can reproduce asexually and in general they are all females. larvae live in the soil and eat roots, which can cause wilting and death of the plant, larvae have white body and brown head.

Outdoor life cycle in the Netherlands: the first generation of larvae are found in April / May in the soil and in April / May / June there will be pupating in the soil.

Adult beetles are to be seen from late May to early August and eggs are in the soil from July until September. The second generation of larvae are in the soil from late July to early September. In greenhouses several generations per year

natural enemies: Heterorhabditis bacteriophora

hosts: e.g. Azalia, Camelia, Fuchsia, Hedera, Liguster, Rhododendron,Taxus

Otiorhynchus apenninus = Otiorhyncus salicicola (Cockchafers)

characteristics: Adult beetles are mostly nocturnal, hiding by day. Adult beetles feed on the leaf margins. The beetles can reproduce asexually and in general they are all females. larvae live in the soil and eat roots, which can cause wilting and death of the plant, larvae have white body and brown head.

natural enemies: Heterorhabditis bacteriophora

hosts: e.g. Hedera, Prunus laurocerasus, Rhododendron, Taxus, various conifer species

Melolontha melolontha (common cockchafer)

characteristics: Imagines (adults) of the common cockchafer reach sizes of 25–30 mm; the forest cockchafer is a bit smaller (20–25 mm). The two species can best be distinguished by the form of their pygidium (the back end): it is long and slender in the common cockchafer, but shorter and knob-shaped at the end in the forest cockchafer. Both have a brown colour. Close up of a male cockchafer, showing the seven "leaves" on the antennae. Male cockchafers have seven "leaves" on their antennae, whereas the females have only six.

Adults appear at the end of April or in May and live for about five to seven weeks. After about two weeks, the female begins laying eggs, which she buries about 10 to 20 cm deep in the earth. She may do this several times until she has laid between 60 and 80 eggs. The common cockchafer lays its eggs in fields, whereas the Forest Cockchafer stays in the vicinity of the trees. The preferred food for adults is oak leaves, but they will also feed on conifer needles. The larvae, known as "white grubs" or "chafer grubs", hatch after four to six weeks. They feed on plant roots, for instance potato roots. The grubs develop in the earth for three to four years, in colder climates even five years, and grow continually to a size of about 4–5 cm, before they pupate in early autumn and develop into an adult cockchafer in six weeks. The cockchafer overwinters in the earth at depths between 20 and 100 cm. They work their way to the surface only in spring. Because of their long development time as larvae, cockchafers appear in a cycle of every three or four years; the years vary from region to region. There is a larger cycle of around 30 years superimposed, in which they occur (or rather, used to occur) in unusually high numbers (10000s).

natural enemies: Heterorhabditis bacteriophora

hosts: They feed on plant roots, for instance potato roots.