Pine processionary Pine processionary The pine processionary ("Thaumetopoea pityocampa") is a moth of the family Thaumetopoeidae. Sometimes placed in the genus "Traumatocampa", it is one of the most destructive species to pines and cedars in Central Asia, North Africa and the countries of southern Europe. The urticating hairs of the caterpillar larvae cause harmful reactions in humans and other mammals. The species is notable for the behaviour of its caterpillars, which overwinter in tent-like nests high in pine trees, and which proceed through the woods in nose-to-tail columns, protected by their severely irritating hairs, as described by the French entomologist Jean-Henri Fabre.
Oak "Lymantria dispar", which can defoliate oak and other broadleaved tree species in North America. A considerable number of galls are found on oak leaves, buds, flowers, roots, etc. Examples are oak artichoke gall, oak marble gall, oak apple gall, knopper gall, and spangle gall. A number of species of fungus cause powdery mildew on oak species. In Europe the species "Erysiphe alphitoides" is the most common cause. A new and yet little understood disease of mature oaks, acute oak decline, has been reported in parts of the UK since 2009. Oak processionary moth ("Thaumetopoea processionea") has become a serious threat