Symptoms
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Feeding damage to buds, needles; total defoliation April to June; mainly on spruces and other conifers, more rarely on deciduous trees; caterpillars spinning threads, yellow to dark grey, with black central line and tufts of hairs as well as two red warts; moth: 35-55mm, white forewings, numerous black, zigzag running cross lines; antennae long and combed; flight period summer (night!); egg deposition in summer in bark cracks; caterpillars hatch in the following spring; after the feeding activity pupation in cocoons in bark cracks.
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Impact
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Economically important pest, mainly of spruce and pine, tendency to mass propagation; total defoliation leads to death of conifers of all ages; lower intensity to loss in increment; furthermore trees can be disposed to secondary invaders; in Austria epidemics occurred during the Sixties and Seventies in the Waldviertel.
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Control
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Repeated check of population in endangered areas by use of pheromone traps, by counting eggs and moths; hygienic measures: removal of infested trees; chemical, biotechnical and biological control measures (see Official Register of Plant Protection); preventive measures: no afforestation with susceptible tree species in monocultures, better establishment of mixed stands with broadleaved trees.
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Hosts |
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All tree species;
Beech;
Spruce;
Pine;
Larch;
Fir;
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Affected plant parts
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Leaf;
Needle;
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