Symptoms
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Leaves, leaf scales, needles: initially skeletonizing feeding pattern (lonly leaf veins remain), later on all tissues eaten by caterpillars; egg layers sponge-like on the stem bark, yellowish-white, palm-sized; caterpillars up to 70mm in length, densily coated by hairs, brown, yellow longitudinal lines or one broad, brown stripe; the first five segments with two blue button-shaped warts, the others with red warts. Imago: female white with brownish zigzag-shaped stripes and black dot; wingspan 50-70mm; male darker (grey-brown) and smaller (wingspan 35-50mm)
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Impact
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Primarily occuring on oaks, occasionally also on other broadleaved trees, rarely on conifers; repeated total defoliation may cause the death of a tree; in most cases trees are only weakened, but predisposed to attacks by secondary damaging agents! Hardly any possibility of errors, as long as egg sponges are present.
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Control
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Control of young caterpillars with Bazillus thuringiensis-compounds; also biotechnical skinning inhibitors (for instance DIMILIN possible (see Official Register of Plant Protection); removal of the egg-sponges from the stem and from branches in winter; male moths can be attracted with pheromone-traps.
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Hosts |
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Maple;
Birch;
Beech;
Edible chestnut;
Oak;
Ash;
Ex-Robinia;
Spruce;
European Hornbeam;
Hazel;
Hemlock;
Pine;
Thuja;
Linden, Lime;
Poplar;
Fir;
Elm;
Walnut;
Willow;
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Affected plant parts
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Leaf;
Needle;
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