hairs containing an irritant chemical, thaumetopoein. Simple contact with the hairs of the caterpillar can cause severe rashes (urticaria) and eye irritation in humans and other mammals, and some individuals may have an allergic reaction. When stressed or threatened, fifth-stage larvae eject hairs shaped like harpoons, which penetrate all areas of exposed skin nearby and irritate them with an urticating protein. Forestry damage The pine processionary is a major economic pest in coniferous forests in southern Europe, where the caterpillar is responsible for most of the defoliation seen in coniferous trees; outbreaks are somewhat cyclical, with a period of 7 to 9 years. Although pines are the most susceptible, other conifer trees such as larches are also vulnerable. The caterpillars can completely defoliate trees if large numbers are present. Global warming is causing the species to affect forests progressively further north. It has for example been a pest of forests in Southern Europe since classical times, but it has already reached the north of France. Artificial control Efforts to control the pine processionary have included biological control using Bacillus thuringiensis, which is effective on eggs and first- or second-stage caterpillars (in September or October), or insecticides such as diflubenzuron, an insect growth regulator, which can be sprayed from aircraft. Monitoring can include the use of pheromone traps. Other methods that have been tried include insecticides in oil inserted directly into nests, and mechanical removal of nests. Notes References External links Wildlife in France: Pine processionary moth Thaumetopoeinae Moths described in 1775 Moths of Europe Taxa named by Michael Denis Taxa named by Ignaz Schiffermüller Articles containing video clips