Processionary Caterpillars in Spain.

These amazing Caterpillars actually transform into a Moth and are one of the most destructive species to pine trees. These Caterpillars have urticating hairs, and will give you or your pet a nasty sting, similar to a nettle/bee/wasp sting and can cause serious and harmful reactions to humans and other mammals.

The adult Moths lay their eggs in Pine trees, and there are millions of them in Spain. The nests, built during the winter months, look like a large ball of grey silky cotton wool and can often been seen in the tops of the pine trees.

Once the larvae have hatched, they eat the pine leaves as they develop through their five stages of growth.

When do they leave the nests?

Around April, these caterpillars leave the nests in a procession for which they are more commonly known.

They then burrow underground and emerge at the end of summer. The eggs are laid and are covered in scales that come from the female to imitate the pine shoots.

The processionary Pine Caterpillar will make several temporary nests, which are usually flimsy, until they reach the third stage of development, when they build a permanent nest. The nests have no openings so the caterpillars have to force their way in.

Why are they marching in a procession?

Hundreds of Caterpillars can join a procession as they search for a pupation site and can travel long distances before they bury themselves in the soft ground to form their cocoons.

It is towards the end of their growth that the hairs on these caterpillars become very irritating to the skin and can cause severe skin rashes and allergic reactions.

These caterpillars can eject their hairs, which have a harpoon type barb on them, particularly when they are stressed or threatened and the poison contained in them, if eaten by a pet, can be deadly.

Take extra care when walking your dogs.

Be extremely careful when taking your dogs for a walk. It is quite easy for a dog to walk on hairs left by these Caterpillars. If the dog then licks it’s paws and transfers the hairs to their mouth and nose, reactions can occur such as severe swelling of the tongue and mouth and you will need to seek immediate medical attention for your pet. 

The tongue, lips, nose and head can become so swollen that the swelling can rapidly block the dog’s airways and the tongue may need to be amputated.

Homeopathic remedies.

The vet may well prescribe APIS Mellifica pills. (A homeopathic remedy used to treat swelling attributed to stings, such as bee and wasp stings).

If you get some of these APIS pills and keep them with you from February to April, you might just save your dog’s life if it does inadvertently eats or plays or walks onto hairs left by the caterpillars.

How to get rid of them!

The only real way to get rid of these processionary caterpillars is to burn them. Don’t go burning the nests in the trees or you are likely to cause a major fire. Wait until they are on the ground.

Removing the nests and burning them is another option but be very careful and seek professional advice, as these nests will contain hairs that can cause you severe pain.

There are Caterpillar trapping kits that wrap around the tree and as the caterpillars descend from the tree to search for soft ground, they are trapped. They can be expensive – around €45 each, so culling Caterpillars in lots of trees with these kits may no be the best option.

Chemicals such as anti caterpillar insecticides are also available.