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Vine weevil

Othiorhynchus sulcatus

Adult weevils feed at night producing telltale notches around the edges of leaves and flowers. The damage is most severe when caused by the voracious larvae, feeding on roots. Heterorhabditis-System provides rapid and effective control of vene weevil.

Biology - Black vine weevil

Adult vine weevils are 8-12 mm long, have a grooved, dull black shell with patches of tiny yellow bristles. As they are well camouflaged and only active at night, they are seldom seen. If they are discovered, they play dead very convincingly.

Outdoors, adult vine weevils emerge from the soil from May onwards. They are wingless, but walk and climb exceedingly well. Male weevils do not occur here. The freshly emerged females feed for about ten days, then commence laying the unfertilized eggs close to well-selected plants. Each female lays about 500 eggs, which are very small (0.8 mm diameter) and round. Initially, these eggs are white, but they turn brown as they mature. As adults are relatively long-lived, egg-laying can extend well until October.

Eggs hatch in 8-20 days, and the tiny emerging larvae burrow deep down into the compost. The larvae are C-shaped and legless. They have a creamy white colour with a shiny brown head. When fully grown, they are 10-14 mm long.

Vine weevils overwinter as larvae, which pupate in spring as temperatures rise. These pupae are cream-coloured and soft bodied. They are found in cavities several centimetres down in the soil. Adult weevils emerge some 3-4 weeks later. In heated glasshouses, the life-cycle is completed more rapidly and several different stages of vine weevil may be found at any time of the year.

Damage

Adult weevils feed at night producing telltale notches around the edges of leaves and flowers. This is often the first sign of vine weevil activity. The damage is most severe when caused by the voracious larvae of the vine weevil. Emerged from the eggs, they feed on little roots. As they grow, they gradually attack bigger roots, tubers, rootstocks and even strip bark from woody stems. As a result, the damaged plant wilts and dies off.

Sometimes, it takes a long time before damage is determined. At that moment, the plant is often already severely weakened and beginning to die off. Slow growing plants, which are unable to compensate for loss of root tissue are most subject to damage.

Crops frequently attacked include:

	Rhododendron, Azalea, Camellia, Taxus
	Many herbaceous perennials
	Certain pot plants, e.g. Cyclamen, Fuchsia and Primula
	In arboriculture: conifers ...
	Strawberries

Beneficials

Heterorhabditis megidis

Heterorhabditis-System is based on a unique strain of the insect parasitic nematode Heterorhabditis megidis, which seeks out and destroys vine weevil larvae in compost.