The Pine Processionary (Thaumetopoea pityocampa) is a species of Lepidoptera (butterfly) native to the Mediterranean basin. Its name refers to the Indian thread of its caterpillars. The caterpillars build nests in pine trees, feeding on their needles. They can lead to massive defoliation and can reduce the productivity and growth of infested trees. In spring, they descend from the trees to bury themselves and complete their chrysalis cycle on the ground. However, beware of stinging hairs! They can trigger allergic reactions in humans and animals.