Pine Processionary Caterpillars in Spain: The Danger to Dogs
By Andrew Turner — exclusive agent in Jávea since 2007 · DGS Registry C0467B54657010 · Last reviewed June 2026
If you own a dog on the Costa Blanca, Costa del Sol or anywhere near pine trees in Spain, the pine processionary caterpillar (oruga procesionaria del pino) is one of the most dangerous things your pet can encounter — and most British and northern-European owners have never heard of it until it is too late. A single lick can cost a dog part of its tongue, and in severe cases it is fatal. This is a practical English-language guide: what they are, when they are active, how to recognise the danger, the emergency first aid that can save your dog, and how pet insurance fits in.
Get a Pet Insurance Quote →What are pine processionary caterpillars?
They are the larvae of the pine processionary moth (Thaumetopoea pityocampa), a moth common throughout the pine forests of Mediterranean Spain. Through autumn and winter the caterpillars live communally in unmistakable white, candyfloss-like silken nests high in pine trees. When the weather warms they leave the nest and descend to the ground in long, nose-to-tail “processions” — dozens of caterpillars marching head-to-tail in a line — to find soft soil where they bury themselves and pupate. It is this descent and procession that brings them into contact with dogs, children and walkers.
They are widespread across the pine areas of the Costa Blanca (around Jávea, Denia, Moraira, Calpe and inland), the Costa del Sol, the Balearics and much of inland Spain — essentially anywhere there are pine trees.
When are they dangerous? The season
The danger period is late winter into spring, typically February to April, though it varies each year with the weather. After a mild winter they can come down as early as January, and a cold snap can push the processions into May. Warmer winters driven by climate change have made the season start earlier and last longer in many areas. The single most dangerous moment is when the caterpillars are on the ground in procession, because that is when a curious dog is most likely to sniff or mouth them.
Key point: even outside the procession, a nest in a tree overhead is a hazard, and the danger does not need direct contact — see below.
Why they are so dangerous: the stinging hairs
Each caterpillar is covered in thousands of tiny, barbed stinging hairs (urticating setae) loaded with an irritant protein called thaumetopoein. When the caterpillar feels threatened it fires these hairs into the air. They work like microscopic harpoons: they embed in skin, gums, tongue, eyes and airways and release the toxin, causing an intense inflammatory and allergic reaction. Crucially, you do not have to touch the caterpillar to be harmed — the hairs are light enough to be carried on the breeze, and a discarded nest or even the ground where caterpillars have passed can still be contaminated.
The danger to dogs — this is the serious one
Dogs are at the highest risk because they investigate the world with their nose and mouth. A dog that sniffs, licks or bites a caterpillar gets a mouthful of stinging hairs, triggering a rapid and severe reaction. This is a veterinary emergency — minutes matter.
Typical signs, which can appear within minutes:
- Sudden, heavy drooling and frothing at the mouth
- Pawing or rubbing at the mouth and face, distress and restlessness
- Swelling of the tongue, lips and face
- The tongue turning dark, blue or grey in patches — a sign of tissue death (necrosis)
- Vomiting, fever and lethargy
- In severe cases, parts of the tongue can die and slough off, and swelling of the airway can be life-threatening
Left untreated, the toxin can cause permanent loss of part of the tongue (affecting a dog’s ability to eat and regulate temperature) and, in the worst cases, death from anaphylaxis or airway obstruction. Do not wait to see if it settles — treat it as an emergency.
First aid: what to do if your dog touches one
If you suspect contact, act immediately:
- Rinse the mouth and tongue with plenty of water at once. Use a syringe, bottle or hose and flush gently and repeatedly. Warm water is fine. The goal is to wash the hairs out before more toxin is released.
- Do not rub the mouth, tongue or skin — rubbing breaks the barbed hairs and drives them in deeper, making it worse.
- Protect yourself — wear gloves if you can, because the hairs will sting you too.
- Get to a vet immediately, phoning ahead so they are ready. Tell them it is suspected processionary caterpillar contact. The vet will give pain relief, anti-inflammatories, antihistamines or steroids and monitor the airway and tongue.
Rinsing buys time, but it is not a substitute for the vet. Every minute counts.
Danger to people and children
People are affected too. Skin contact causes an itchy, raised rash and hives; the hairs in the eyes cause painful conjunctivitis; and breathing them in can cause throat irritation, coughing and, in sensitive or asthmatic people, more serious respiratory reactions. Never touch a caterpillar, a procession or a nest, keep children well away, and do not let anyone poke or burn nests without protection (see below). If you have a strong reaction, especially around the eyes or breathing, seek medical advice.
How to protect your dog
- Know your area and the season. If you live near pines, be on alert from January through spring.
- Look up and look down. Scan pine trees for the white silk nests, and scan the ground for processions before letting your dog off the lead.
- Keep dogs on a lead near pine woods during the season, and steer well clear of any caterpillars on the ground.
- Do not let dogs sniff at the base of pines where caterpillars gather to bury themselves.
- Have nests removed professionally. Many town halls treat public pines; for your own garden, use a licensed pest-control company.
Dealing with nests — do not DIY burn them
It is tempting to burn a nest, but burning or knocking down a nest releases a cloud of the stinging hairs and is dangerous to you, your family and your pets. Removal is a job for professionals, who use the right protective equipment and methods (physical removal, pheromone traps on trunks, or banded traps that catch the descending procession). Many Spanish municipalities run treatment programmes on public land — report nests to your ayuntamiento.
Does pet insurance cover processionary caterpillar treatment?
Emergency treatment for processionary-caterpillar poisoning — the vet consult, medication, and any follow-up care for tongue or skin damage — is exactly the kind of unexpected, urgent cost a good pet insurance policy in Spain is designed for. It is one of the more common spring emergency claims for dogs on the Costa Blanca and Costa del Sol. A comprehensive policy covers accident and illness vet fees, so a single incident does not leave you facing a large bill at the worst possible moment.
Remember too that dog third-party liability insurance is now compulsory in Spain under the 2023 animal-welfare law (Ley 7/2023) — a separate but essential cover. If you need to make a claim, here is how to claim on your pet insurance, and you can always contact our English-speaking team for help. As an exclusive Generali agent, we can review your pet cover and make sure your dog is properly protected for the spring.
Frequently asked questions: processionary caterpillars in Spain
Make sure your dog is covered this spring
Processionary season is a costly time for dog owners. We arrange English-speaking pet insurance in Spain with emergency vet cover and the compulsory dog liability — and we are happy to review your existing policy.
This guide is general information, not veterinary or insurance advice. If you suspect your dog has had contact with a processionary caterpillar, contact a vet immediately. Insurance cover varies by policy — we are happy to review yours.