Pine Processionary Caterpillars in Mallorca: Danger for Dogs, Children and Gardens

The pine processionary moth on Mallorca is no exotic curiosity, but an introduced insect that has lived on the island since 1942 and repeatedly poses a danger to dogs, children and pine trees. The caterpillars of the moth Thaumetopoea pityocampa carry fine urticating hairs that, on contact, can trigger allergies, skin irritation and, in the worst case, eye damage – in both humans and pets. In this guide you'll learn how to recognise affected pines and migrating caterpillar processions, why dogs in particular are at risk due to their sniffing and licking behaviour, what the Balearic authorities are doing to combat the pest, and what you can do on your own property – as well as what's best left to the professionals.

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What is the pine processionary moth – and why is it found on Mallorca?

The pine processionary moth is not a native species in the Balearics. According to the Servei de Sanitat Forestal, the specialist body of the Conselleria de Medi Ambient i Territori within the Govern de les Illes Balears, it is an introduced, invasive insect that appeared successively on all four major islands. The name "processionary moth" refers to the caterpillars' characteristic mode of movement: they always travel in groups, one behind the other, forming the eponymous "processions".

The caterpillars feed on the needles of all pine species – explicitly including the Aleppo pine (Pinus halepensis), which is native to Mallorca. In cases of heavy or repeated infestation, or when the trees are already weakened, this can cause serious damage to the tree population.

Life cycle: from egg to moth

To correctly assess nests and periods of danger, it helps to look at the animal's life cycle: the moths that hatch in summer produce eggs, which overwinter on pine needles. In spring, the caterpillars hatch from these and develop through several moults. In the course of their development, the caterpillars form the feared urticating hairs containing the irritant substance – caution is therefore advisable throughout the entire caterpillar season, regardless of the developmental stage. Once development in the tree is complete, the caterpillars leave the pine to pupate in the soil. In summer, the rather inconspicuous moths emerge from the pupae, mate, and start the cycle anew.

Recognising nests and processions

The caterpillars build conspicuous, whitish-silky web nests in the pine crowns, where they develop over the winter. Towards the end of winter and in spring, they leave these nests together and are then often seen travelling in long, unbroken lines – on the ground, along path edges or across open areas. It is precisely during this migratory phase that direct contact is most likely, since the animals are no longer high up in the tree but moving at eye level with humans and dogs.

Note: Even old, already abandoned nests and leftover moulted skins can still contain urticating hairs. A nest with no visible caterpillars is no reason to let your guard down.

When is the critical period?

The exact activity period varies with weather and altitude; milder winter spells can favour their development and cause the caterpillars' procession to start earlier. You are most likely to encounter them in pine and pine-tree stands – at woodland edges, on rural paths, in larger gardens or in natural-style grounds. Anyone who regularly walks through such areas with a dog or children should pay particular attention during the cold season and the start of the warm season, looking both up into the crowns and down onto the path.

Health risk to people

The Servei de Sanitat Forestal describes the effect of the urticating hairs unambiguously: in sensitive individuals they can trigger allergic reactions, cause hives-like irritation, and in the worst case lead to skin and eye damage. The official recommended course of action is correspondingly simple: do not touch the caterpillars and be careful in affected pine stands.

Why dogs are especially at risk

For dogs, the situation is trickier than for people for a simple reason: they sniff, lick and put things in their mouths. This means urticating hairs caught on paws or fur come into direct contact with the mouth, tongue and mucous membranes – areas that react more sensitively than skin. If you suspect your dog has come into contact with a caterpillar, its hairs or a nest, one clear rule applies: go to the vet immediately, don't wait, and don't try to treat or give anything yourself. You can find an overview of veterinary practices on the island in our veterinary practices directory. General information on keeping dogs in Mallorca is gathered in our Pets.

Caution: If you suspect contact has occurred, don't wait for visible symptoms. Go straight to the nearest veterinary practice or emergency clinic.

Protecting children and the garden

The same applies to children: don't touch caterpillars or nests, and don't poke them with sticks or tools either. Anyone with a finca or house with their own pine trees should regularly check play areas in the garden for nests in the tree crowns and for processions of caterpillars moving along the ground, especially before children picnic or play outdoors. You'll find general tips on garden maintenance on the island in our guide Garden Mallorca.

Official pest control on Mallorca

On publicly used land, the Servei de Sanitat Forestal combats the pine processionary moth as part of a multi-year project involving ground-based treatment. The measure is carried out by the public company IBANAT.

Note: The most recently published project explicitly runs from 2021 to 2025. Whether and in what form the campaign will be extended in subsequent years is announced by the authority at the start of each season – rely on the notices issued by the Servei de Sanitat Forestal for current dates.

In cases of heavier infestation or emerging infestation hotspots, ground-based treatment is proposed in the relevant official declarations, among other things, as a measure of public benefit. Questions about specific areas or the course of the campaign are answered directly by the specialist body.

What you can do on your own property

On private property, restraint is the right strategy. Cutting off nests yourself, vacuuming them up, or even burning them is not a good idea: handling them releases urticating hairs that spread through the surrounding area, and an open fire poses an additional fire risk during the dry season. It's more sensible to hire a specialised professional company to remove them properly. You'll find general advice on dealing with pests around the house in our guide Pests in the house.

Most common mistakes

• Touching caterpillars or nests to "take a closer look" – the urticating hairs come loose even with slight contact.
• Waiting to see with a dog whether "it gets better on its own" – if contact is suspected, the direct route to the vet is the way to go.
• Burning or vacuuming nests yourself – increases the spread of the urticating hairs and poses a fire risk.
• Letting children poke at nests or caterpillar processions with sticks – even from a "safe" distance, hairs can be stirred up into the air.
• Assuming old, empty nests are harmless – moulting remnants can still contain urticating hairs.

What happens after contact?

After a visit to the vet or medical advice, you should continue to monitor the affected area – in dogs as in humans – and avoid repeated contact in the same area as long as nests or caterpillar processions are still visible there. Clothing, dog leads or toys that came into contact with caterpillars or nests should be thoroughly cleaned before being used again. If symptoms persist – in humans or animals – seeking a fresh professional assessment is more sensible than waiting it out.

Checklist for dog owners and families

1. During the transition from late winter to spring, deliberately avoid pine paths or keep the dog on a lead within sight.
2. When out walking, keep an eye on both the treetops and the edge of the path.
3. Before sitting down under pines, glance upwards briefly and check the ground.
4. After every walk near pines, quickly check your dog's paws and coat.
5. If contact is suspected, contact a vet immediately – do not attempt self-treatment.
6. Do not remove nests on your own property yourself; hire a specialist company instead.
7. Teach children early on not to touch caterpillars or nests.

Conclusion

The pine processionary moth has been part of Mallorca for over eighty years – its danger lies not in bites or stings, but in tiny urticating hairs that can trigger serious irritation on contact. For dog owners, the most important rule is simple: if contact is suspected, go straight to the vet, don't wait. On public land, the Servei de Sanitat Forestal, together with IBANAT, takes care of control as part of a multi-year campaign; on your own property, you're well advised to use a specialist company and stay alert during walks. There's no need to avoid pine forests altogether – but during the critical season, you should walk through them with your eyes open.

Official sources

• Govern de les Illes Balears – Conselleria de Medi Ambient i Territori, Servei de Sanitat Forestal: https://www.caib.es