What are processionary caterpillars?
Pine and oak processionary caterpillars are insects that live in colonies in pine or oak trees. They get their name from the fact that they follow each other in single file. Their proliferation can weaken trees.
The hairs of these caterpillars are extremely irritating. They can cause inflammatory reactions, mainly affecting the skin (redness, itching, skin pain, localised oedema, hives and sometimes small blisters), eyes (conjunctivitis, eye watering, eye pain) and respiratory tract (coughing, respiratory discomfort), which can sometimes be serious in the exposed people or animals. You can suffer symptoms even without touching the caterpillar, as it can shed its stinging hairs, which are then carried very easily by the wind.
The pine processionary caterpillar is found over a very large part of France, primarily in the south, centre and west of the country. It is mainly seen between January and May.
The oak processionary caterpillar is most common in the north-east, the Paris region and north-western France, but may also be found in southern regions. It is mainly seen between April and July.
Together with the poison control centres, ANSES analysed the various cases of adverse effects associated with stinging hairs from processionary caterpillars, reported in France between January 2012 and July 2019. The results are available in the November 2019 issue of Vigil'Anses (PDF) (in French).
How can you protect yourself from processionary caterpillars?
Here is some advice on how to limit the risks of irritation associated with processionary caterpillars:
- do not approach or touch the caterpillars or their nests: this applies especially to children;
- keep away from trees containing their nests;
- wear long clothing when walking in the forest or near infested trees;
- avoid rubbing your eyes during or after a walk;
- wash fruit and vegetables from your garden thoroughly if there is any known infestation nearby;
- avoid drying laundry next to infested trees;
- if you suspect you have been exposed to the caterpillars, take a shower and change your clothes;
- in the event of any signs of a life-threatening emergency (respiratory distress, etc.), dial 15 (in France) or go to the nearest hospital emergency unit;
- if any symptoms of caterpillar irritation occur, seek advice from a doctor or call a poison control centre;
- if you come into contact with a caterpillar, take photos of it for easier identification;
- if pets are affected, seek advice from a veterinarian or call one of the veterinary poison control centres (the Western France Animal and Environmental Poison Control Centre [CAPAE-Ouest] or the National Information Centre for Veterinary Toxicology [CNITV]).