The processionary caterpillar: who is it? What to do in case of irritation?


The processionary caterpillar represents a danger for humans and animals due to its highly stinging hairs. The irritant substance released by the insect causes severe irritation to the affected areas. While amputation is sometimes unavoidable, the vital prognosis can also be engaged.

Who is the processionary caterpillar?

Brown with orange reflections with a black band on the back, the pine processionary caterpillar (Thaumetopoea pityocampa) is a butterfly larva belonging to the order of Lepidoptera and to the family of Notodontidae. In summer, the larvae transform into butterflies which will lay up to 200 eggs on the branches of conifers (pines and firs). The insect frequents three-quarters south of France but tends to move up north each year with global warming. These caterpillars are considered harmful in several ways: for the farmers whose crops they destroy, for the conifers they damage, for humans and animals which can develop allergic reactions to their contact. The Lepidoptera owes its name to its movement in procession, that is to say in line.

Processionary caterpillar: what makes it poisonous?

The processionary caterpillar passes by five larval stages before reaching its final size of about 4 cm. Non-stinging when they hatch, the larva then takes on microscopic harpoons-shaped hairs, placed in small pockets – called mirrors – located on his back. When the caterpillar feels threatened, its mirrors open and release a cloud of very allergenic bristles which become embedded in the epidermis. If you scratch yourself, the hairs break and release an extremely stinging toxin into the body: thaumetopoein. This substance toxic causes lesions on all affected body surfaces.

What dangers does the processionary caterpillar represent?

Animals are the first victims of the attack of processionary caterpillars and in particular dogs who like to poke around for truffles on the ground. A contact with the stinging hairs causes in a few minutes a inflammation coupled with irritation, even a violent reaction of the allergic type. This burning sensation will cause the dog to scratch and lick, spreading the micro-hairs on his body and in his mouth, then adding edema and pain. Thaumatopoein rapidly affects the lips and areas made up of thin skin. The face of the animal may swell as well as its tongue. Without medical intervention, the possible development of ulcers causes necrosis part of the tongue which will then blacken and then detach from the healthy area. Hyper-salivation and vomiting are often observed. Anaphylactic is another consequence: this allergic reaction causes breathing difficulties which may prove fatal for the animal.

Processionary caterpillar bites: how to react?

If your dog has obviously come into contact with processionary caterpillars, you will have to react very quickly while keeping your cool. What to do ?

  • Put on gloves plastic to protect you because by handling your dog, you risk infecting yourself (and having to consult a doctor in turn);
  • Prevent your dog from scratching and licking itself otherwise it will make the situation worse;
  • Rinse his tongue and eyes with plenty of water. Emphasize the paws, muzzle and ears but without rubbing because by breaking the stinging hairs, the condition of the animal will worsen;
  • Take your dog to the veterinary. If her office is closed, go to an emergency department.

Processionary caterpillars: what veterinary treatment?

If your dog has been bitten by processionary caterpillars, the veterinarian will perform various treatments depending on the symptoms. The priority is to oxygenate the animal in case of throat edema to avoid suffocation. Then the professional will rinse the dog’s mouth with a solution specific to eliminate stinging hairs without breaking them. By reducing the passage of the toxin into the blood, the local lesions will stop spreading. An injection of corticosteroids fast-acting will help reduce tissue necrosis. An ophthalmologic examination will be performed because an envenomation of the eyes is a serious injury, often irreversible. Of painkillers will also be prescribed to reduce the suffering of the animal. In most cases, a dog quickly taken care of by a veterinarian has little or no after-effects (limited amputation of the tongue, for example). On the other hand, a language completely necrotic leaves no other choice than euthanasia for the dog who is unable to eat and drink. In the case of bites by processionary caterpillars, an immediate visit to the veterinarian is therefore a matter of vital emergency.