If you're used to walking in the woods or spending time in your garden, then you've probably already seen them. I'm talking about processionary caterpillars, tiny insects that move in single file. Since 2010, oak and pine processionary caterpillars have been gaining ground in France, particularly in Paris itself and throughout theÎle-de-France region, where their numbers are steadily increasing. According to ARS Île-de-France, colonies of both oak and pine processionary caterpillars have been observed in the region since the early 2000s. " Present on 1% of the Ile-de-France territory in the early 2000s, they have now established themselves on just over 80% of the region.
However, these small caterpillars, also known as stinging caterpillars, are particularly dangerous for humans and animals, as they can cause severe inflammatory stinging reactions. By decree, processionary caterpillars have been classified as a species harmful to human health.
Although discreet, these little beasts pose a considerable danger to the people of Paris and our four-legged friends. What makes them special? Stinging hairs charged with thaumetopoein, a protein capable of provoking intense inflammatory reactions.
The presence of these caterpillars in the capital is well established, particularly in the Bois de Boulogne and Bois de Vincennes and in several key arrondissements. Their period of activity, extending from late winter to early spring, is a critical window of opportunity during which you'll need to be particularly vigilant. Indeed, when they leave their arboreal habitat to burrow, caterpillars can easily come into contact with humans and animals, intentionally or unintentionally.
What are processionary caterpillars?
There are two types of processionary caterpillar, starting with the oak processionary caterpillar(Thaumetopoea processionea), which can be dangerous from April to July. It is mainly found in the northeast quarter of France.
Then there's the pine processionary caterpillar(Thaumetopoea pityocampa), which is worth keeping an eye on between January and May. It is mainly present in ¾ of southern France, and its migration front moves up a few kilometers each year.
Both species of processionary caterpillar live in groups, in nests attached to trees. After hatching, they move around in processions. Their proliferation can cause " weakening of trees ", according to Anses, the French national agency for food, environmental and occupational health and safety. What makes them special? Their stinging hairs, which can be particularly dangerous.
Processionary caterpillars: what are the health risks?
Because of their stinging hairs, processionary caterpillars can cause severe inflammatory reactions to the touch. But these stinging hairs can also " break off very easily in the wind or on contact ", explains ARS Île-de-France. These hairs can therefore be transported over long distances, and " easily attach themselves to tissues (skin and mucous membranes), causing urtication (the stinging sensation that accompanies hives) through the release of histamine (a substance also released in allergic reactions) ".
Direct contact with these processionary caterpillars is therefore not the only factor behind these inflammatory reactions. " These stinging properties persist even after the caterpillar has disappeared ", adds ARS Île-de-France.
The regional health agency also specifies the different types of symptoms developed in the event of contact with these insects, such as itching on the skin, but also conjunctivitis (red, painful, watery eyes). In the event of contact by inhalation, sneezing, sore throat, difficulty swallowing and possibly breathing difficulties may occur. In the event of an allergic reaction, be sure to seek prompt medical attention.
According to a study carried out by Anses between January 2012 and July 2019, 1,022 cases of exposure to processionary caterpillars were recorded by poison control centers.
These insects can also be very dangerous for animals, such as dogs and cats. If ingested, they can cause tongue necrosis and even death.
Processionary caterpillars: how to protect yourself?
On its website,Anses unveils a number of steps to take and offers advice on how to avoid stinging inflammatory reactions.
To begin with, avoid infested areas during the risk season, wear covering clothing when walking in these areas, and of course, never attempt to touch or move these insects. In fact, it's advisable not to approach or touch caterpillars or their nests, especially children. Avoid walking under nest-bearing trees. Note that you don't need to be in contact with a caterpillar to show symptoms: its stinging bristles, which detach following mechanical contact or when the caterpillar feels attacked, are easily transported by the wind.
Avoid rubbing your eyes during or after a walk. If you have a garden, be sure to wash your fruit and vegetables thoroughly. Finally, avoid drying laundry next to infested trees.
Aware of the scale of the problem, municipal services have put in place targeted intervention strategies. The removal of nests and the installation of specific traps are among the measures adopted to limit the proliferation of caterpillars. Encouraging populations of chickadees, the natural predators of these insects, is also an effective complementary ecological method.
In the event of accidental exposure, the reflexes to adopt are clear: wash thoroughly and change clothes to eliminate residual hairs. Symptoms of skin or eye irritation require immediate medical attention. And in the event of more serious reactions, call emergency numbers immediately. For signs of life-threatening emergency (respiratory distress, severe allergic reaction, etc.): call 15 or 112.
To sum up, to reduce the risk of processionary caterpillar poisoning, follow these recommendations:
Official website
www.iledefrance.ars.sante.fr
