The Dangers of the Pine Processionary Caterpillar

As we are travelling with a springer spaniel and a german shepherd dog who are both very inquisitive and love wandering around sniffing, we have made sure we are fully versed with the dangers of these little critters and in the unlikely event one of our dogs came across them we would know exactly what to do. We are by no means specialists on this subject, we just want to make as many people aware of the dangers. We have read several articles and we had no idea that something that looks so innocent like a small hairy caterpillar could be so dangerous to humans and animals.

During January/February if you walk past a pine tree in Spain and a lot of other areas in Europe you will probably see the silky nests which are usually at the tip of the branches on the pine tree. Some nests are small and only the size of a 50 pence piece but most nests are a similar size to a grapefruit and hold about 300 caterpillars. The nests are usually located on the south facing side of the tree and there are usually several nests in one tree. So far we have seen nests in Moraira, Calpe and Benidorm. I think it seems safe to say, if there are pine trees about they will more than likely have the caterpillars in them.

The caterpillars tend to disperse through the trees at night to feed on the pine needles and then go to the communal nests by day to increase their warmth and digest the food they have eaten.

The time for them to leave the nest for their next life cycle varies with temperature and how hot it is, so in warmer climates it will be earlier than up in the mountainous regions.

During late winter/spring the processionary caterpillars come down out of the trees and form conspicuous snake-like lines. They leave the trees and look for a suitable place to burrow underground where they will undergo the transformation to turn into moths.

It is as they leave the trees that they are more likely to come into contact with humans/pets and sometimes with very painful consequences. The caterpillars are quite large at 3-4 cms each and are very noticeable when on the ground as they form a snake like procession and the line usually ranges from 1-2 metres long.

The danger they pose to humans/pets is a simple defensive mechanism designed to stop them being eaten themselves. Each caterpillar is covered with tiny barbed hairs, it is these which cause the harm. It is important for humans not to touch the nests or go to close to them as the hairs are constantly being dropped while the caterpillars are in the trees and of course the nests are loaded with them.

The main danger to dogs are if the dogs stand on the caterpillars or sniff them. If the tiny hairs get on the paws, they will cause irritation and your dog will lick them. Once the hairs are on the lips/tongue it will induce itching, swelling and possibly vomiting. Noticeable symptom’s are white spots in the mouth/tongue, excessive drooling and chomping.

It is really important to get your dog to a vets as quickly as possible. In the interim, try and rinse the area with water immediately. Getting your dog to a vets is a must as in some cases partial amputation of the tongue is the best course of action.

We are not going to let these caterpillars ruin our time in Spain. We are making sure we give pine trees as wide a berth as we can. If we are in the vicinity of them the dogs are kept on a short lead and away from the trees. On arrival to a new area as a precaution we make sure we are aware of where the local vets are and that we have their contact details and emergency telephone number to hand.