Pine Processionary Caterpillars in Spain: The Danger to Dogs
By Andrew Turner — exclusive Generali agent since 2007 · DGS Registry C0467B54657010 · Last reviewed May 2026
Every spring across Spain, one of the prettiest-looking creatures in the pine woods becomes one of the most dangerous — especially for dogs. The pine processionary caterpillar can cost a dog part of its tongue, or its life, and it harms people too. This guide explains how to recognise them, when they are active, and exactly what to do in an emergency. For the vet bill, see how pet insurance helps, or get a quote.
Get a Free Quote →What are pine processionary caterpillars?
The pine processionary (Thaumetopoea pityocampa) is the larva of a moth that lives in pine trees throughout Spain — very common on the Costa Blanca, Costa Cálida and across inland pine country. You will recognise two unmistakable signs:
- The nests: dense white silk balls, like clumps of cotton wool, hanging in the branches of pine trees through autumn and winter.
- The processions: in late winter and spring the caterpillars leave the nest and move across the ground in long head-to-tail lines — nose to tail, sometimes dozens long — which is where the name comes from.
Each caterpillar is covered in thousands of microscopic barbed hairs that release an irritating toxin (thaumetopoein) on contact. The hairs detach easily and are even dangerous airborne or after the caterpillar is dead.
Why they are so dangerous to dogs
Dogs are the most common — and most serious — victims, because their instinct is to sniff, paw and lick the caterpillars moving along the ground. Contact with the mouth, tongue or nose drives the toxic hairs into soft tissue, and the reaction is fast and severe:
- Sudden, intense drooling and salivation
- Swelling of the tongue, lips and muzzle, often within minutes
- Pawing at the mouth, restlessness and pain
- In bad cases, necrosis (tissue death) — parts of the tongue can turn dark and slough away
- Vomiting, fever, and in severe cases breathing difficulty or shock
A dog can permanently lose part of its tongue, and without prompt treatment the reaction can be fatal. This is never a “wait and see” situation.
When are they active in Spain?
The danger period runs across the cooler months:
- Autumn & winter: the white nests build up and are visible in the pines.
- Late January to April: the caterpillars descend and form their processions on the ground — the most dangerous phase for pets and children. Warmer winters bring them down earlier, sometimes from December.
Climate change has been pushing the season earlier and extending the caterpillar’s range northwards and to higher altitudes, so do not assume an area is safe just because it once was.
What to do if your dog makes contact
- Rinse the mouth repeatedly with warm (not hot) water. Wear gloves, and pour or splash rather than rub — rubbing breaks more hairs and spreads the toxin.
- Do not let the dog lick the affected area or swallow the rinse water if you can avoid it.
- Do not use home remedies or try to neutralise the toxin yourself — get to the vet.
- Call your vet on the way so they are ready; out of hours, find the nearest emergency clinic (clínica veterinaria de urgencias).
Protecting your dog — and yourself
- Keep dogs on the lead in or near pine areas during the danger season.
- Scan the ground for processions and the trees for nests before letting a dog off-lead.
- Never touch caterpillars or nests with bare hands. In people the hairs cause itchy rashes, eye irritation and breathing problems — and reactions can be severe in children.
- Do not remove nests yourself. Disturbing a nest releases clouds of airborne hairs. Use a professional pest-control firm or your local ayuntamiento, which handle removal and tree treatment safely.
How pet insurance helps with the vet bill
Emergency treatment for processionary poisoning — the consultation, medication, and any follow-up for tongue damage — is exactly what a pet policy’s vet-fee cover is designed for. Spain also now requires dog third-party liability insurance under Ley 7/2023, and a full pet policy adds the vet-fee protection on top. As authorised Generali agents in Jávea, we arrange pet insurance for dogs and cats across Spain, in English. Read our pet insurance guide, contact us, or call 966 461 625.
Frequently asked questions
Are pine processionary caterpillars dangerous to dogs?
Yes — they are extremely dangerous and contact is a veterinary emergency. Their barbed hairs release a toxin that causes intense swelling and tissue death. A dog that licks or mouths one can lose part of its tongue, and without fast treatment it can be fatal.
What time of year are processionary caterpillars active in Spain?
Their white silk nests are visible in pine trees through autumn and winter. The caterpillars descend in head-to-tail processions, usually between late January and April depending on the weather — warmer winters bring them down earlier. They are most dangerous on the ground during this descent.
What should I do if my dog touches a processionary caterpillar?
Treat it as an emergency and go to a vet immediately. While preparing to travel, rinse the dog’s mouth repeatedly with warm water, wearing gloves and being careful not to rub (which spreads the hairs). Do not let the dog lick the area. Time matters — the toxin works fast.
Are processionary caterpillars dangerous to humans?
Yes. The hairs cause itchy skin rashes, eye irritation and, if inhaled, breathing difficulties. Reactions can be severe in children and in anyone allergic. Never touch the caterpillars or their nests with bare hands, and keep children well away.
Does pet insurance cover processionary caterpillar poisoning?
A pet policy with vet-fee cover is designed for exactly this kind of accidental emergency — the consultation, treatment and any follow-up care. Cover and limits vary, so check the vet-fee limit when you take out the policy. Turner Insurance can arrange Generali pet cover in English.
How do I get rid of a processionary nest?
Do not remove a nest yourself — disturbing it releases clouds of airborne hairs that are hazardous to people and pets. Use a professional pest-control company or your local council, which handle nest removal and tree treatment safely.
Sources & references
- Ministerio para la Transición Ecológica (MITECO) — information on procesionaria del pino and forest health.
- Ley 7/2023 (BOE) — the Animal Welfare Law and mandatory dog liability cover.
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This guide is general information, not veterinary or personalised advice. If you suspect your pet has touched a processionary caterpillar, contact a vet immediately. Cover and limits vary — for advice on pet insurance, contact Turner Insurance.