The processionary caterpillar: a real danger for dogs and children

Updated: March 14, 2025

Every Spring, it's the Same Story with the Pine Processionary Caterpillar

Imagine you're at the park with your dog. The weather's great, and as always, he's running, playing, and sniffing where he shouldn't... suddenly, he comes across some pine processionary caterpillars on the ground. They catch his attention, he sniffs them, or, even worse, tries to eat them. A little later, he starts to drool uncontrollably, his tongue swells, and if you don't act fast, it could be too late.

This happens every year, especially in spring, and most people have no idea of the risk present in parks and forests. So let's get serious and explain it properly, because this is important.

What is the pine processionary caterpillar and why is it so dangerous?

The pine processionary caterpillar (Thaumetopoea pityocampa) is that line of caterpillars you see moving in a row on the ground, like a miniature train. But what looks like a harmless parade is, in reality, an extreme danger for dogs, children, and adults.

Dangers of the pine processionary caterpillar

Each of these caterpillars is covered in thousands of urticating hairs that, as soon as they come into contact with skin or mucous membranes, release a powerful toxin. And be careful, you don't even need to touch them directly: these hairs can detach and travel through the air, so if you get too close, they can irritate your eyes or cause respiratory problems.

- For dogs: The pine processionary caterpillar for dogs can be fatal. If they lick or bite one, their tongue swells, and if action is not taken quickly, it can become necrotic.

- For humans: It is not lethal, but it can cause allergic reactions, severe skin irritations, and respiratory problems.

- For children: They are especially vulnerable because they tend to touch everything. In case of contact, they can suffer more severe reactions than adults.

Pine processionary caterpillar: effects and symptoms of a very dangerous pest

For adults, it can leave a bad burn on the skin or a rather annoying allergic reaction, but for a dog, contact with the pine processionary caterpillar is a race against time.

Effects of the pine processionary caterpillar on dogs and humans

In dogs:

- Severe inflammation of the tongue and mouth.

- Excessive drooling and intense pain.

- Necrosis of the tongue (it can fall off in pieces).

- In severe cases, anaphylactic shock and death.

In humans:

- Skin irritation with redness and blisters.

- Respiratory problems if the urticating hairs are inhaled.

- Severe conjunctivitis if they get into the eyes.

Symptoms a dog shows if it comes into contact with the pine processionary caterpillar

If you see your dog with any of these symptoms, act fast:

- Excessive drooling, as if poisoned.

- Swollen, red, or bruised tongue.

- Scratching its mouth with its paws.

- Difficulty breathing.

- Lethargic state, as if dozing.

- Vomiting and general discomfort.

How to act in case of possible poisoning?

- Don't waste a second: Take the dog to the vet immediately.

- Wash the mouth with lukewarm water (never rub, it could spread the toxin further).

- Do not try to remove the hairs by hand: Use gloves if necessary.

The vet will administer anti-inflammatories, antihistamines, and, in severe cases, may require corticosteroids or even surgery to remove necrotic tissue.

How to eliminate the pine processionary caterpillar?

If you have detected caterpillars near your home, do not touch or step on them. Use a leash and a harness during walks to keep your dog under control at all times; in this case, it's a matter of life or death. I wouldn't risk it.

Also, do not try to burn them, because the urticating hairs spread with fire. The best way to eliminate the pine processionary caterpillar is:

- Call professionals: Pest control services know how to eliminate caterpillars safely.

- Prevent them from falling from the tree: Place special traps on tree trunks in advance to prevent them from descending and becoming moths.

- Cut and destroy nests in winter, when the caterpillars are in the larval stage and not yet dangerous.

How to prevent the appearance of the pine processionary caterpillar?

If you want to prevent these caterpillars from invading your area, there are several measures you can take:

- Pine tree control: The pine processionary caterpillar lays its eggs in pine trees. Keeping trees healthy and applying preventive treatments can reduce their population.

- Natural predators: Birds like titmice or bats feed on these caterpillars. Encouraging their presence can be a good strategy.

- Pine tree vaccination: There are specific treatments to protect trees and prevent the proliferation of the pest.

- Biological control: There are fungi and bacteria that attack the pine processionary caterpillar without affecting the environment.

How to protect your dog from the pine processionary caterpillar?

- Avoid areas with pine trees in spring, which is when the caterpillars come down to the ground.

- Always keep your dog on a leash in risky areas.

- Teach your dog not to sniff or lick anything suspicious.

- Check the ground carefully before letting him off leash.

The pine processionary caterpillar is not just an annoying insect. It is a real danger, especially for dogs, who can die if they come into contact with it. Now that you know how to eliminate caterpillars and how to act in an emergency, protect your dog and stay alert in parks and forests.

If you see a group of caterpillars in a line, do not approach them. And above all, do not let your dog do so. Their life could depend on it. Call 112 or Seprona and indicate exactly where you found them; it will be easier for specialists to eradicate them.

Thank you for your interest in this post. We encourage you to take a look around our tQel website, and check out all the new products we have for your dog.

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