nest of processionary thaumetopoea pityocampa in pine tree

nest processionary caterpillar thaumetopoea pityocampa bag silk stinging hairs larva insect pest chrysalis metamorphosis colony gregarious pine conifer tree branch leaf needle crown forest pine vegetation nature ecosystem environment rural countryside garden park damage defoliation allergy irritation sting danger threat biological control treatment prevention invertebrate lepidoptera life cycle biology