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Kahl trees and shrubs on the way, - Roads and forest edges as well as in parks and gardens are mostly the work of small butterflies of the genus Yponomeuta - the so-called Gespinstmotten (Yponomeutidae). In Central Europe over 50 species of insects occur, they occur on various trees as pests. The names are given by the fine webs in which the caterpillars, which are harmless to humans, are mated individually or in groups, depending on the species. The veil can over time cover whole bushes and trees.
As a result of climate change, gypsy moths are increasingly occurring in large numbers, as moths prefer dry and warm weather. The animals are also very resistant to low temperatures.
Caterpillars fly between June and August, depending on the species. Then the insects deposit their egg shingles in their typical roof tile-like arrangement on branches and young shoots of the affected plants. The moths cover their eggs with a protective secretion, which hardens quickly. After a few weeks, the light gray or cream-colored offspring hatches. Then the little caterpillars cover the trees and shrubs with fine, silvery webs to protect themselves from predators like birds or weather like heavy rain. In the webs live up to hundreds of larvae, which eat the trees empty with great appetite. Subsequently, the vermin pupate from the beginning to the middle of June in the protection of the web. About two weeks later, the first adult moths fly.
The webs can wrap whole trees and shrubs in a net
After mating, the moths lay their eggs back on the buds of the plants, where they can easily survive until the next spring. The development of the pest can last undisturbed up to ten years. Typically, gypsy moths develop one generation per year.
Detect cobweb moths
The approximately one-centimeter sized moths have white-gray wings with black dots on them. Her hind wings are gray; closed they form a steep roof. The moths have a wingspan of up to 25 millimeters. Cotten moths are to be distinguished from the dreaded oak-processioners. The most striking distinguishing feature is the lack of hair on the body of the gypsy moths.
The larvae are characterized by a dark green to brownish color. Their bodies can be subdivided into ten segments, each with a black dot on its sides. Also, the head of the caterpillars is black and on their backs are characterized by the incidence of light through the slightly transparent body, the offal as a brown line. In addition, her body is dotted with isolated, fine hairs.
The larvae of the Gespinstmotte occur mostly in groups. In mass production they can spy whole plants, eat bald and damage them
In case of heavy infestation, the host plants are eaten by the gypsy moths completely bald. The trees are then completely covered with a white web. In general, however, the trees recover quickly and drive around the so-called Johannistrieb on 24 June again, without sustaining lasting damage. Exceptions are fruit trees whose yield can be significantly lower.
With a mass occurrence of Gespinstmotten the damage picture is not to be overlooked. Whole trees can be enclosed by the webs and the caterpillars eat the plant completely bare
Frequently affected plants
Especially on bird cherries there is a strong mass infestation every few years due to the caterpillars of the bird cherry-spider moth (Yponomeuta evonymella). But hawthorn, Pfaffenhütchen, poplars or willows are often affected. Fruit trees such as the apple tree are also attacked by the apple caterpillars (Yponomeuta malinellus). This species is a serious pest in fruit growing - especially when natural predators are absent - and should therefore be tackled immediately when they occur. Since the respective Gespinstmotten are specialized on certain tree species, they do not go normally on other trees over.
Only when fruit trees such as apple and plum are heavily attacked by the spider moth, a fight against the pest is necessary. The remaining trees and shrubs usually do not cause much damage from an infestation with the moth. An infestation is often only recognizable when the small caterpillars have already formed their white webs. The control with a pesticide is then difficult because the fine mesh structure of the web would roll off the sprayed agent. Thus, the preparation does not penetrate to the caterpillars and they remain undamaged.If no webs have yet formed, it is possible to combat the pest with the aid of preparations based on Bacillus thuringiensis or with other bee-compatible agents.
As a precaution, in winter you can scrape off the eggs of the insects from the affected trees and shrubs. Also remove the leafy leaves in the spring and dispose of them in the residual waste. Cut all webs and caterpillars out of the trees and shrubs as early as possible and dispose of them. It is also possible to spray the braids with a powerful jet of water.
Natural antagonists of the gadfly moth, for example, are different types of parasitic wasp
Also promote natural antagonists of the gadfly moth such as parasitic wasps and robber bugs. They prevent the unchecked spread of the pests. The beneficial insects feel particularly well in a natural garden.