Agelastica alni
Blue alder leaf beetle ( Agelastica alni )
The alder leaf beetle or blue alder leaf beetle ( Agelastica alni ) is a species of the family of leaf beetles ( Chrysomelidae ). She is the only one of its kind in Europe. On occasion, the animals to a mass occurrence in the alder can be completely defoliated.
Features
Alder leaf beetles are six to seven millimeters long and have a slightly stocky build. The widest part of the upper side everywhere dense and fine point-like structured body lies behind the middle of the elytra, the pronotum is narrower than this. He is laterally rounded at the sides and has a hem, his slice is without impressions. The hem of the top wing is well and fairly recognizable. The body of the animals is blue-black, dark blue, blue violet or greenish colored. The antennae and legs are black. The head bears a striking impression between the antennae. The third member of the probe is shorter than the fourth. The species can most likely with blue colored individuals of the Erzfarbenen alder leaf beetle ( Linaeidea Aenea ) are confused, which can be distinguished in particular by their prominent Schulterwülste on the elytra, however.
Occurrence
The species is widespread in the Palaearctic and was introduced in the Nearctic. In northern Europe, the spread reaches up to Central Fennoscandia, in England the way also partly in the Alpine region is rare. The animals colonizing alder at the edge of water bodies and wetlands. They generally occur very often.
Way of life
Imagines and larvae feed on leaves of alder. The females lay on the undersides of leaves nest at 60 to 70 eggs. From them hatch in about two weeks, the black-colored young larvae that live then socialized. Only later divided into individual leaves. Young larvae feed only one side of the leaves ( feeding window ), older larvae eat holes. Pupation takes place three to five inches deep in the ground in a doll's cradle. The new generation of beetles emerges in July and feeding on the alder leaves before they hibernate in the fall. Only one generation is formed per year.