Caterpillars can kill you

It’s that time of year again, and I don’t mean Valentine’s Day. I mean the time when Spain’s most dangerous creatures appear.

I’m talking about the Pine Processionary caterpillars that make nests in the pine trees of Spain. Don’t underestimate them, they are deadly. Keep your pets away from them, and don’t try to destroy them yourself. 

If you are holidaying in Spain at this time of year, BEWARE.


Caterpillars walking in a line

An excerpt from ‘Two Old Fools ~ Ole’  which explains how Joe and I became aware of these creatures.

The shrine stood in the centre of a clearing at the top of the mountain. It was freshly painted and flowerbeds had been planted all around. Several benches stood beneath waving pine trees and glorious views stretched out over the mountains in all directions. I happened to look down at the ground a few feet in front of us.

“What’s that?” I asked, pointing.

Joe stood up and walked over, crouching down to examine the curious spectacle I’d spotted.

“Oh my gracious aunt!” said Joe. “What on earth…”

Writhing along the ground was a long, brown sinuous worm-like thing. Except it wasn’t a worm, or even a snake. It was a six-feet long line of caterpillars, marching nose to tail.

We were enchanted. Each caterpillar was brown with yellow stripes and soft downy hairs. Each caterpillar followed the one in front, never deviating from the line, never getting left behind. We stayed awhile, fascinated, watching the determined little procession.

“I wonder what type of caterpillar they are?” said Joe. “And I wonder where they’re heading?”

The answer to these questions was to come as a bit of a shock…

We took some photos, headed back down the hill, pausing briefly to chat with Geronimo’s donkey, then went home. I switched on the lap-top and described our caterpillar encounter on Twitter. And what a response I got!

‘@VictoriaTwead They’re KILLERS! Don’t go near them!’

‘@VictoriaTwead Hate them, hate them, hate them!’

‘@VictoriaTwead What is the point of those evil things?’

‘@VictoriaTwead Those caterpillars are DEADLY, avoid at all costs!’

I was a little taken aback… Killers? Deadly? How could those cute little fluffy caterpillars be anything but charming? My Internet research took me to the Grazalema Guide which has an excellent article on these sinister little creatures.

I read the article. The caterpillars we had encountered were Pine Processionary caterpillars, destined to hatch into unremarkable moths. The female moth lays her tiny eggs in a pine tree. The eggs hatch and the caterpillars grow quickly, feeding voraciously on pine needles at night. To protect and house their community, they spin a white fluffy bundle in the tree and in February or March the entire colony abandons the tree in a long line searching for soft soil to bury themselves and pupate. This procession was what we’d observed on our walk.

So why the horror? Well, if disturbed, the caterpillar sheds its hairs. The hairs cause painful rashes, or much worse. If inhaled, the tiny hairs can be lethal. An inquisitive dog unfortunate enough to inhale them needs to be rushed to the vet within 40 minutes. Children and adults can also suffer severe reactions, including anaphylactic shock. Even walking under trees housing the bundles can be dangerous as the hairs are often airborne.

Clearly these critters are not to be messed with. I read with horror and huge sympathy the comments people had left on the forum:

“My Yorkshire has just come in contact with the Caterpillars and it’s not looking good as her tongue is inflamed and she is passing blood. We had her in the vet and they said the next 48 hours will decide if she is to survive.”

“My five month old labrador puppy has lost nearly half his tongue which dropped off and is now suffering the effects of all the drugs he has taken. He has devloped two large lumps on his side. He is ok but don’t under estimate the effect of theese caterpilars.”

“Thank you for this info. I live in the Algarve Portugal and work at a local vet. Unfortunatly we have to treat many dogs and occasionally cats that have been affected by the caterpillar. Their tongues go neucrotic and sometimes the end may drop off. We have to wait a few days to check that the animal can still eat and drink with the remaining part of the tongue.”

The last comment on the website made me smile simply because it seemed to me that this particular guy had had a very lucky escape.

“I came across thousands (and I’m not exaggerating) of these in Menorca last week. Walking up the sand, on the handrails, on the wooden walk-way and squashed underfoot in their thousands. There were the nests in the nearby pine trees as you described and, looking at the photos above they appear to be the same. However if they are the same then I’ve been remarkably lucky. I spent ages picking them up and arranging them to get a good photo. I also was curious to know what they did when you moved them from their chosen trail etc.”


As if these horror stories weren’t enough, the pine trees themselves are devastated by these furry fiends, and often die. The next time we hiked up the mountain, I examined the area much more carefully. The caterpillars had gone, but sure enough, we could see the white bundles dangling from the trees, just as the article described. And amongst the clump of pine trees stood dead ones, already stripped by the caterpillars. We resolved to warn the villagers and keep the Ufarte twins away from the area.

Read more in Two Old Fools ~ Ole!