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Alder leaf beetle - Agelastica alni
Alder leaf beetle - Agelastica alni

Alder leaf beetle
The alder leaf beetle (Agelastica alni) belongs to the genus Agelastica, in the order beetles (Coleoptera), the suborder Polyphagan beetles (Polyphaga), the infraorder Cucujiformia, the superfamily Chrysomeloidea, the family leaf beetles (Chrysomelidae) and in the subfamily Galerucinae. Scientific synonyms for Agelastica alni are: Adimonia violacea, Cryptocephalus violacea and Chrysomela alni.
Agelastica alni - Side view
Agelastica alni - Side view
In Central Europe the alder leaf beetle is commonly encountered and as only representative species of the genus Agelastica. In fact it is found almost everywhere in the Palearctic. It does not occur in the Alps. Agelastica alni reproduce once a year and are not endangered.
Alder leaf beetle - Rear view
Alder leaf beetle - Rear view
The alder leaf beetle is relatively small. It reaches body lengths of 5-7 mm. Its oval, compact body is very rounded and widens at the hind end. It has a metallic sheen and can be black, black-blue, steel-blue, dark-green or violet in colour.
Alder leaf beetle - Front view
Alder leaf beetle - Front view
The antennae are black, long and threadlike. The wing covers (elytra ) are hairless and are densely covered in fine dots. The alder leaf beetle lives in the most diverse biotopes, is day active, and is found particularly frequently in flat country. It prefers damp areas, in which alder (Alnus) bushes or trees grow.
Agelastica alni
Agelastica alni
The young adult alder leaf beetle leaves its pupa in August and lives off the leaves of various trees and bushes until the end of September. These include alder (Alnus), willow (Salix), poplars (Populus), birch (Betula) and hazel (Corylus). At the end of September - beginning of October the alder leaf beetle hides in the ground, where it overwinters.
Larvae of alder leaf beetle
Larvae of alder leaf beetle
In late April - early May, it appears on alder leaves once more, in order to start the so-called "maturation feeding". Alder can release hormones, which lower digests the beetle and thus forces it to change host. In this way alder are protected from excessive damage to their leaves. The alder leaf beetle then evades on other alder, willow, poplar, hazel, other fruit trees and herbs. These beetles often occur here in great numbers, which can kill younger trees and can limit growth in older trees.
Larvae - Agelastica alni
Larvae - Agelastica alni
In May - June, matingtakes place. Oviposition also occurs in May - June in clutches of 60-70 eggs, which are laid on the lower surface of the leaves of the food plants of the hatching larvae. A female can lay up to 900 eggs. The eggs are approximately 0.5 x 0.9 mm in size, oval to cylindrical in form and ochre-yellow-orange in colour.
Group of Lavae - Alder leaf beetles
Group of Lavae - Alder leaf beetles
After 5 to 14 days the larvae hatch. At the end of the 3rd larval stage they are about 11 mm in length and pupate. The larvae of alder leaf beetles are first olive, later cyan and shortly before pupating bluish in colour. They have 2 rows of very hairy warts. The larvae, like the adult beetles, feed on the leaves of the grey or speckled alder (Alnus incana), hornbeam (Carpinus), birch (Betula) and hazel (Corylus). They feed, initally in groups and later alone, by scraping the surface off the leaves from the underside, leaving only the veins, unlike the adults. eats the leaves from the lower surface by scraping them off. The development of the larvae is complete in 3 weeks (June/July). They pupate in oval spaces in the earth just beneath the surface of the soil, where they remain for 8 to 11 days. In August the beetles of the new generation leave their pupae.

Description of images / photos
Photography with Cameras
Nikon D3x, Nikon D300, Canon 50D
Image editing with Photoshop
1. Alder leaf beetle - Agelastica alni
2. Agelastica alni - Side view
3. Alder leaf beetle - Rear view
4. Alder leaf beetle - Front view
5. Agelastica alni
6. Larvae of alder leaf beetle
7. Larvae - Agelastica alni
8. Group of Lavae - Alder leaf beetles
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