Elm leaf beetle
| Elm leaf beetle | ||||||||||||
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Dutch elm leaf beetle ( Xanthogaleruca luteola ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Xanthogaleruca luteola | ||||||||||||
| ( Müller , 1766) |
The elm leaf beetle ( Xanthogaleruca luteola ) is a beetle from the family of leaf beetles (Chrysomelidae).
features
The beetles reach a body length of about six millimeters. They are yellow to olive green in color and have a black stripe on the outer edge of the wing in addition to a black wing cover seam . Directly on the pronotum, the wing covers each have a black, longitudinally smeared spot between the wing cover seam and the black stripes. Her head and pronotum are also yellow and have black spots in the middle or the pronotum on the sides.
The larvae are about 13 millimeters long. They are greenish or pale yellow with several rows of dots on the back and on the sides. They can also be colored completely black. They are colored yellow on the sides.
Occurrence
The beetles are common in the western Palearctic from Portugal to Central Asia. They were introduced in North America and Australia .
Way of life
The larvae eat the leaves of elms ( Ulmus spec. ) And live mainly on solitary trees. In North America, the leaves of the Chinese elm ( Ulmus parvifolia ) are preferred .
development
The females lay 5 to 25 of their yellow-orange, spindle-shaped eggs together on the underside of the leaves of their host plants, in previously eroded depressions. In total, they lay 400 to 800 eggs. The larvae that hatch from it feed by only scraping the surface of the underside of the leaf. The leaves are skeletonized, but the tops and veins remain intact. Because the dried up leaf areas crumble out after a while, the leaves appear perforated. The development of the animals is complete after about three weeks. They climb down the trunk and pupate in cracks in the bark or other cracks on the trunk. The adult beetles hatch after one to two weeks. The adults hibernate in sheltered places, such as B. under bark, but also in houses and under wooden panels. They reappear in spring to fly to elms, on which they lay eggs for a new generation.
Harmful effect
The animals live in larger groups on their host plants and can partially or completely defoliate them as the heavily eaten leaves wither and fall off. It is true that the trees can quickly develop new leaves after a complete defoliation, but since the beetles remain in the tree, these are also eaten. However, this only very rarely leads to the death of the tree, e.g. B. when the trees are also weakened by diseases and other insects.
