Watch out – The processionary caterpillar season is upon us!


When out walking you've probably noticed large white balls in certain conifer trees.

These are nests of the processionary caterpillar. By the end of winter, these bugs have woven their silk nests, and represent a serious danger for both humans and cats and dogs. On the trees where they have settled, they can also cause significant damage.

Stinging hairs

When the caterpillars leave the nest (usually March-April but sometimes earlier if the weather is warmer) is the most precarious time for our precious pets. They are called processionary caterpillars for the simple reason that as they leave the nest they walk one behind the other interconnected by a silk thread.

These caterpillars are also covered with venomous stinging hairs, which can also float in the air. Contact with the hairs can cause a range of reactions, from mild itching, eczema or eye disorders to significant allergy attacks.

A veterinary emergency

Dogs (especially puppies) and cats are always curious. If they approach the caterpillars to sniff, or worse, to swallow them, the consequences can be disastrous.

The most visible symptom is in the mouth. The tongue begins to swell (this may take several hours), and the blood supply is cut off. When you open the mouth of the animal, the tongue (or part of it) will be grey and / or ulcerated. Eye disorders may also be observed, or the dog or cat may start drooling.

This is a veterinary emergency and time is critical. You can rinse the wound with water (if possible), but first and foremost get to a vet as soon as possible.

If the symptoms are not noticed quickly, the animal may lose all or part of the tongue, which then prevents it from eating or drinking.

chenilles2At home

If you find a nest, you should be extra careful when removing it. Wear a mask, gloves and take all possible protection to avoid any flying hairs. There are chemical or biological insecticides (some are safe for dogs and cats) that can be used in early autumn. In any event, once the nest is dislodged, it must be burnt as quickly as possible.

You can also spray the nest with bleach (one bottle for every 3 litres of water), which does not damage the tree. On shaking the tree, the caterpillars and the nest will fall, and the nest can be burnt. Please bear in mind that the stinging hairs remain active, even after the death of the caterpillar. This is best done in the summer, after the bugs have spawned, but before they build a nest.

The larvae from the caterpillars can survive in the soil for several years, so this process may have to be redone every year.

You have been warned - please take care!