Date Published: 12/02/2025
Pet owners beware: Lethal processionary caterpillars have already made an appearance in Spain
The season for this potentially deadly pest has arrived earlier thanks to the mild temperatures across Spain
The processionary caterpillar season is arriving earlier and earlier each year as global temperatures climb and thanks to
the unseasonably mild winter we’ve been experiencing in Spain, these deadly critters have already made an appearance in towns and cities across the country. When they descend from the pine trees in vast numbers, these insects can prove lethal to pets, and even young children.
So dangerous are these pests that the authorities have issued several warnings on social media:
“Be very careful if you are walking with your dog and you see a processionary caterpillar. It has stinging hairs that can cause a very serious reaction,” said the Guardia Civil on TikTok.
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The National Police added on X: “The processionary caterpillar has come early this year and we must be vigilant in places where there are pine trees.”
The insects get their name from the curious way they move around on the ground. The offspring of Thaumetopoea pityocampa, commonly known as the processionary moth, spend the winters in tent-like nests in pine trees. Once the weather becomes milder, the caterpillars climb down from the trees in a single-file ‘procession’ and form a striking nose-to-tail column once on the ground. They are a sight to behold as they make their way to cover, and so are
especially dangerous when it comes to curious young children and dogs.
Their bodies are covered in around 500,000 tiny hairs called trichomes which they release like poisoned darts when they feel threatened, often into the faces of animals.
“At that moment, it is easy for the trichomes to get stuck in the animal's nose or eyes, causing symptoms such as inflammation, intense itching and abundant salivation. If they eat them (which is not uncommon if they have previously touched one with their paws and lick them because they are itching), the ingestion of the toxic substance that carries their trichomes can cause necrosis of the tongue or throat,” explained the national association of environmental health companies, Anecpla.
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Dog owners are advised against walking their pets through any parks or public gardens with pine trees and if they do come across a procession, they should give it a wide berth. Since the trichomes can also cause skin irritations in humans, a tip is to wear closed-toe shoes and long trousers.
If pets or people develop any symptoms after coming into contact with processionary caterpillars, medical attention should be sought immediately.
Images: Cuidado con la oruga procesionaria
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