Pine processionary development, pine processionary caterpillars are highly irritating to the skin. Contact with the hairs of the caterpillar can cause severe rashes (urticaria) and eye irritation. Some individuals may have an allergic reaction to the caterpillar's hairs. 5th stage larvae can eject hairs when threatened or stressed; the hairs, which have the form of harpoons, then penetrate and irritate all areas of exposed skin nearby with an urticating protein. Allergic reactions may follow in susceptible individuals on subsequent exposure to the hairs. The pine processionary is an economic pest in coniferous forests in southern Europe. It is controlled to some extent
Lepidoptera migration migratory butterflies and moths that reach north-western European countries like the Netherlands, Belgium and the United Kingdom. Research in the United Kingdom confirms that an increasing number of migrants reach the country. Because one would expect that migratory species can adapt to new circumstances quite well, the researches warn for new species that can have a negative impact on native species and possible damage to both health (species like the oak processionary) and agriculture. Lepidoptera migration Many populations of Lepidoptera (butterflies or moths) migrate, sometimes long distances, to and from areas which are only suitable for part of the year.