Middle elm splint beetle
| Middle elm splint beetle | ||||||||||||
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Middle elm beetle ( Scolytus laevis ), female, enlarged 20 times. |
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| Scientific name | ||||||||||||
| Scolytus laevis | ||||||||||||
| Chapuis , 1873 |
The middle elm beetle ( Scolytus laevis ) is a weevil from the subfamily of the bark beetle (Scolytinae). Since it creates its breeding systems in the bark of the host trees, it is counted among the bark breeders.
features
The beetles are 3.5 to 4.5 millimeters long and have a black, cylindrical body. The pronotum is large, narrowed in front, finely dotted, the base and sides are edged. Seen from above, it does not cover the head. The forehead has a short furrow and in the male beetle is flat and densely hairy, in the female beetle it is arched and almost bare ( sexual dimorphism ). The abdomen rises obliquely from the second sternite , which does not have a spinous process, towards the end. The rails ( tibia ) of the front legs are smooth on the outside, the tip is curved like a hook. The third tarsal link is bilobed. The red-brown colored wing covers have two types of rows of dots made up of small depressions. These rows of points are only one point width apart. The seam strip is long and deeply indented.
distribution
The species is distributed in Western Europe except England, Central and Eastern Europe, southern Northern Europe and the Balkans.
Way of life
The middle elm beetle occurs mainly on elms ( Ulmus ), occasionally also on black alder ( Alnus glutinosa ), red beech ( Fagus sylvatica ), Norway maple ( Acer platanoides ), oak , linden , Prunus species, and pears . It colonizes the bark of the trees, especially in the branches. The Wolverine image is a four to ten centimeters long, one-armed mother transition (vertical longitudinal passage), the most with a nuptial chamber begins -like extension, but can be variable. The larval ducts on each side are fine and dense and up to eight inches long. One generation per year is trained. The beetle eats green sprouts when they mature. In doing so, and when boring into the bark, it can transfer spores of the fungus Ceratocystis ulmi . This fungus leads to a disease of the tree, which usually leads to the death of the host tree ( Dutch elm disease ).
Combat
Control is practically impossible because the animals will always have material that is suitable for breeding. Infested trees are usually discovered too late. Foci of infestation must be completely eliminated if one wishes to curb further spread and the bark with the larvae and eggs as well as the infected wood destroyed. In many places, however, the elms have already died on the fungus and are therefore no longer available as a host tree. There have been attempts to cultivate Resista elms to resist the fungus.
literature
- Fritz Schwerdtfeger : The forest diseases. Textbook of forest pathology and forest protection . 4th, revised edition. Parey, Hamburg and Berlin 1981, ISBN 3-490-09116-7
- Sabine Green : Manual for the determination of the European bark beetle Verlag M. & H. Schaper, Hanover 1979, ISBN 3-7944-0103-4
- Edmund Reitter : Fauna Germanica - The beetles of the German Empire. Volume 5, KG Lutz, Stuttgart 1916
- Edmund Reitter: Fauna Germanica - The beetles of the German Empire. 5 volumes, Stuttgart KG Lutz 1908–1916, digital library volume 134, Directmedia Publishing GmbH, Berlin 2006, ISBN 3-89853-534-7
