Health & Safety

Pine processionary caterpillars and dogs: signs, first aid and safer walks in southern Europe

Where they live, when they come down from the pines, what contact looks like, and why it is an emergency.

By 6 min read
Two dogs relaxing outdoors in a garden with a chew toy

If you walk your dog in Spain, Portugal, Italy, Greece or the south of France, you may have seen them: a long line of hairy caterpillars crossing the path under the pine trees, nose to tail. They look harmless, even fascinating. For a curious dog, one sniff or lick can mean an emergency trip to the vet.

Here is what pine processionary caterpillars are, when they are most active, what to do if your dog touches one, and how to plan walks that keep your dog well away from them.

Pine processionary caterpillars are covered in tiny stinging hairs that can cause severe swelling and damage to a dog's mouth and tongue. They live in pine trees across southern Europe and come down to the ground mainly in late winter and spring. If your dog sniffs, licks or eats one, go to a vet immediately. In season, avoid pine woods and keep your dog on a lead.

What are pine processionary caterpillars?

They are the caterpillars of a moth that lives on pine trees, and sometimes on cedars. They are named after the way they travel: in a single line, one behind the other, like a procession.

Each caterpillar is covered in many tiny hairs that break off easily and can even drift in the air. These hairs cause the reaction, not a bite or a sting. Dead caterpillars, old nests and the ground where a procession has passed can still hold hairs, so the risk does not disappear with the caterpillars.

The local names are worth knowing if you need help abroad: oruga procesionaria in Spanish, chenille processionnaire in French, processionaria del pino in Italian and processionária do pinheiro in Portuguese.

Where and when are processionary caterpillars found in Europe?

They are most common around the Mediterranean, and most dangerous to dogs from late winter into spring, when they leave their nests and walk down the trees to bury themselves in the soil.

AreaWhen to take extra care
Southern Spain, Portugal, the Mediterranean islands, southern Italy and GreeceCan start in mid-winter in warm years and continue into spring
Northern Spain, central and northern Italy, southern and western FranceMainly late winter and spring
Further north and on higher groundLater in spring. The caterpillar's range has been spreading north over time
Central and northern Europe, including the Netherlands, Belgium and GermanyA relative, the oak processionary caterpillar, lives on oak trees, mostly in late spring and summer

Timing shifts with the weather and the altitude, so ask a local vet when the season starts where you live or stay. You will often spot the nests before the caterpillars: white, silky balls, like cotton wool, high in the branches of pine trees. They are common in parks, gardens, campsites, golf courses and the pine woods behind many beaches.

What happens if a dog touches a processionary caterpillar?

The hairs cause a fast, painful reaction, usually in the mouth, on the tongue and around the face. Dogs are most often affected when they sniff, lick or try to eat a caterpillar, so the tongue takes the worst of it.

Watch for these signs, which usually appear within minutes:

  • Sudden, heavy drooling
  • Pawing at the mouth or face
  • A swollen tongue, lips or face
  • Whining, restlessness or obvious pain
  • Vomiting
  • Red, itchy skin or sore eyes
  • Difficulty breathing or swallowing, in severe cases

In serious cases, part of the tongue can be permanently damaged, and swelling in the throat can affect breathing. That is why contact is always an emergency, even if your dog only seems mildly bothered at first.

What should I do if my dog touches one?

Go to the nearest vet immediately, and call ahead on the way so the clinic is ready for you.

  1. Move your dog away from the caterpillars, and keep other dogs and children back too.
  2. Do not touch the hairs with bare hands. Use gloves or a cloth if you need to handle your dog's face.
  3. Do not rub the mouth or face. Rubbing breaks more hairs and pushes them deeper into the skin.
  4. Phone the nearest vet and say it is a processionary caterpillar, so they know it is urgent. They may ask you to rinse the mouth gently with water on the way. Only do this if they advise it and it does not slow you down.
  5. Get there fast. Early treatment gives your dog the best chance.

Save the number and address of your nearest emergency vet before you set off on walks, especially when you are on holiday somewhere new.

How can I protect my dog on walks?

Keep your dog away from pine trees during the season, and keep them on a lead wherever pines grow. Prevention is far easier than treatment.

Do

  • Keep your dog on a lead in pine woods and parks in season
  • Scan the path and the base of trees for lines of caterpillars
  • Look up for white, silky nests in the branches
  • Choose routes away from pines, such as open fields, beaches where dogs are allowed, or streets
  • Ask neighbours or your vet when the season starts locally

Avoid

  • Letting your dog sniff around the base of pine trees
  • Walking under trees with nests in late winter and spring
  • Touching, sweeping or burning caterpillars yourself
  • Resting or picnicking under infested pines
  • Letting your dog dig in pine needles or soil under pines in season

If you have pine trees in your garden, check them for nests in autumn and early winter. Do not remove nests yourself. Many town councils and professional pest services can treat or remove them safely, and in some areas there are local rules about who should do it.

Planning a winter or spring stay on the Costa del Sol, the Algarve or in Tuscany? Add processionary caterpillars to your checklist, along with the paperwork in our guide to travelling in Europe with your dog. Our guide to ticks and dogs covers another spring risk in many of the same areas.

What can my dog do instead of a pine-wood walk?

A shorter walk on safe ground, plus some enrichment at home or on the terrace, keeps your dog content during the high season. Sniffing, licking and chewing tire dogs out more than you might expect.

  • Take a slow street walk and let your dog sniff at their own pace. Our guide to sniff walks for city dogs explains how.
  • Scatter part of your dog's dinner on a clean terrace or in a pine-free part of the garden, so they can hunt for it.
  • Practise a few minutes of simple training, like sit, wait and touch.
  • Give a frozen toy after the walk, filled with part of their usual food.
“My podenco is obsessed! Really great dog toy/ snack / multifunctional ice lolly”
Sue P., verified buyer

Spring often brings warm spells in the south too. For ideas on cooling fills, see the Freezbone recipe videos and our list of mistakes to avoid in the hottest days of summer.

Are people and cats at risk too?

Yes. The hairs can cause itchy rashes and sore eyes in people, and young children who pick up caterpillars are especially at risk. Cats can also be affected, though they are less likely to meet a procession than a dog on a walk. If a person has a strong reaction, seek medical advice.

Know the season, look up at the pines, and keep the lead on. With a little planning, your dog can still enjoy every walk the Mediterranean has to offer.

General information, not veterinary advice. If you're worried about your dog, talk to your vet.

Frequently asked questions

  • Severe reactions can be life-threatening, especially if swelling in the mouth or throat affects breathing. Some dogs also lose part of their tongue. Going to a vet immediately gives your dog the best chance of a good recovery.

  • Yes. The white, silky nests in pine branches hold caterpillars and their stinging hairs, and even old, empty nests can still contain hairs. Keep your dog away from fallen nests and the ground under infested trees.

  • Mainly in late winter and spring, when they leave the nest to bury themselves in the soil. In warm coastal areas this can start in mid-winter, while at higher altitudes and further north it tends to happen later in spring. A local vet can tell you when the season usually starts in your area.

  • It is safer not to. Disturbing a nest releases the hairs, which can affect you, your family and your pets. Contact your town council or a professional pest service, as rules on removal vary from place to place.

  • The pine processionary is mainly found in southern Europe, though its range has been spreading north. A relative, the oak processionary caterpillar, lives on oak trees in parts of central and northern Europe, including the Netherlands, Belgium and Germany. Its hairs are also irritating, so keep your dog away and see a vet if contact happens.

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Written by Freezbone Team

We design freezable, refillable natural-rubber chew toys and test every fill and routine on our own dogs before we write about it. Freezbone Limited ships across the European Union from Ireland.

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