The oak processionary moth turns out to be a harmless moth at the end of July, beginning of August. Its history, however, makes you sit up and take notice, because before that it was a larva – and in a certain phase of its existence it can become an unpleasant contemporary. In the district of Hassberge, the animals were discovered and professionally removed at the outdoor swimming pool in Ebern, at the playground in Unterpreppach, near Konigsberg and at the school center in Hassfurt, among others – which is sometimes necessary, especially near populated areas.
Because: From the third larvae stage, which according to the Nature and Biodiversity Conservation Union of Germany, they reach “already from the end of April/beginning of May” the insects form stinging hairs that contain a nettle toxin. If people or animals come into contact with it, it can become unpleasant.
This experience, for example, Dr. Klaus Mandery has already made this experience. The biogeographer from Ebern is, among other things, chairman of the Hassberge district group of the German Nature Conservation Union and managing director of the Institute for Biodiversity Information Ebern. Insects are his specialty – he has already spotted the oak processionary moth (EPS) on numerous excursions in the Hassberge district. “I know a whole series of nests”, he says.
The skin reddens and hurts
During the research work he had already come into contact with the stinging hairs and that was admittedly painful. The nettle poison caused an allergic reaction on the skin, red pustules formed, but the symptoms subsided after a few hours. However, depending on predisposition and possible allergies, the stinging hairs can also cause worse skin or eye irritations, in some cases even allergic shocks.
Especially when such nests are discovered near kindergartens, residential areas/cycle paths (as in June between Konigsberg and Unfinden), on playgrounds (as was the case in May in Unterpreppach), or as – also this year – on a sunbathing lawn in the Ebern open-air swimming pool or at the school center in Habfurt, it makes sense, according to Mandery, to remove them because of the possible health hazard. Anyone who discovers such a nest should report it to the responsible local authority, which will then decide whether it needs to be removed.
However, it is not necessary to panic about the EPS in general, says Mandery. Although the caterpillar, which nests almost exclusively on oak trees, is considered a pest because of its voracious appetite, the insect is still part of the ecosystem, serving as food for other animals in virtually all stages of life (see info box). Besides a fight, in particular if chemical means are used, is always connected also with concomitants, by which other animal and plant kinds are damaged, says Klaus Mandery.
Forest stand: when to combat?
The EPS is also active in the forests of the Habberge district. This year, however, it was not necessary to combat the pest across the board, as Jurgen Hahn, senior forestry advisor at the Office of Food, Agriculture and Forestry (AELF) in Schweinfurt, explains. Measures are therefore weighed up very carefully; only when a threat to the oak forests is apparent is the pest combated, for example with pesticides. But this is “the last resort. No one from the forest administration likes to spray poison in the forest”, he says.
Nevertheless, this was necessary once this year, but not because of the EPS, but because of the gypsy moth. According to Hahn, the moth is even more aggressive in its feeding behavior than the EPS and also attacks other tree species. On a forest area of about 100 hectares between Mechenried (Riedbach) and Rugheim (Hofheim), the caterpillar species massively threatened the stands. The agent is then targeted in the breeding areas by helicopter sprayed to stop the caterpillars.
Natural enemies of the oak processionary moth
Background The following information is taken from the background paper “Oak processionary moth” (EPS) of the Federal Nature Conservation Agency Germany. The file is available on the Internet at www.nabu.de available for download.
Delicious, Part 1 While bats and birds prey on adult moths, the caterpillars are eaten by only a few bird species. Beside the hoopoe, which is rare in Germany, above all the cuckoo is a prominent opponent also of later caterpillar stages. These cannot harm it with their poison, because it has the ability to choke out its stomach lining with the stinging hairs stuck in it.
Tasty, Part 2 Significant predators continue to be predatory beetles such as the great pupa predator, caterpillar flies, ichneumon wasps, and braconid wasps. While the pupal predator preys on the caterpillars, the flies and wasp groups mentioned above harm the EPS parasitically by having their larvae develop inside the caterpillars (as well as in those of other butterfly species).