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Danger to Pets: the Pine Processionary Caterpillar in Portugal

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Danger to Pets: the Pine Processionary Caterpillar in Portugal


Written by  Laurinda Seabra
Friday, 22 September 2017 10:31

The Pine Processionary Caterpillar (Thaumetopoea pityocampa) is a common pest found in pine trees all over Portugal, especially in the spring months of the year.

This means that both residents and visitors should be on their guard when the caterpillars or larvae, who have nested in pine trees, hatch out and make their way in a close procession line down the pine tree trunks to the ground.

Nests are fairly easy to spot since they are white, tent-like silk structures near the ends of branches, so when you spot these, be vigilant for any brown (yellowish) and black striped hairy caterpillars strolling down pine trees, in the ground or in surrounding paths. In spite of caterpillars normally being found in large groups, individual caterpillars do tend to drop out of the nests, so be vigilant for any when you are near pine trees.


Be aware that the caterpillars are covered in lots of short hairs, and these hairs cause nasty allergic reactions on contact with human skin.


Severe problems result only when the hairs come into contact with the mucous membranes of the eyes or mouth. In these cases, the reaction is so severe that it can cause cellular death and loss of large areas of tissue.

For pets, such as dogs, which normally are curious by nature, contact with the tongue, gums or throat can cause life threatening swelling almost immediately followed by potential loss of the tongue a few days later. Cats tend not to investigate with their mouths as readily as dogs, but they will lick hairs off their paws or coat and experience similar effects. It is important that pet owners seek treatment for their pets at a vet as SOON as possible.

Intravenous medication can be given to halt the process of the reaction but the earlier this is done, the better your pet’s chances of survival. You may not actually see your pet with the caterpillars, but be suspicious if you encounter ANY of the following signs:

  • Sudden distress, whining and agitation
  • Sudden frantic licking or gnawing at one area of the body- often a paw
  • Pawing at the eyes or mouth
  • Rubbing the face along the ground
  • Excessive drooling
  • Mouth hanging slightly open and seems unable to close
  • The pet struggles to swallow or breath.


First aid

This is an emergency and the dog should be placed under a vet's attention as soon as possible. But as first aid, it is advisable to flush the dog's mouth with plenty of water. Be sure to remember that the poison is also harmful to humans, so be sure to wear protective gloves.



  • Stay away from areas where you know there are a lot of nests during the months of Spring.
  • If you like walking near pine trees, we strongly recommend that you keep your dog on a leash during the period that the caterpillars are known to be around.
  • If you see your dog or your cat walk over any caterpillars, or coming in close contact with any of them, do everything you can to prevent them from licking their paws, and immediately go and wash them with soap and water.
  • You can also try to remove any visible caterpillar hairs using “Sellotape” before wetting the area.


And as a final word, if you are not sure if the caterpillars have affected your pet, just get your pet to a vet immediately. Do not wait …


To read more about the pine processionary caterpillars click here




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