If you live in Spain or visit during the spring time, you might have heard people talking about the processionary caterpillar. This creature is often mentioned in forums by dog owners who have seen them out on their walks and are warning others of the danger.
It’s a real threat too. We don’t usually associate caterpillars with the potential to kill, but these creatures have caused the death of many dogs and other animals and have made their presence felt amongst their adult owners too.
What are they?
The pine processionary moth flies around May to July and only lives for about one day during which time it must mate and lay its eggs in the foliage of a pine tree. A single female can lay up to 300 tiny eggs and it takes around a month for them to hatch.
Once they have hatched, the minute caterpillars have five growth stages called ‘instars’. During their third moult or instar they build the white cotton-wool like nest and continue to feed on the pine leaves until the fifth instar. This usually happens any time from February to April.
At this point, the caterpillars (procesionaria del pino) make their way to the ground in a long chain searching for the next place in their life cycle. This behaviour gives them the name of the ‘processionary caterpillar’. You can recognise them by their distinctive orange-brown colour and blue bands.
Eventually they will disperse to burrow just below the ground where they will pupate. Before this happens they can be a danger to humans and other mammals. It is the hairs of the caterpillars that can cause problems. If they are touched or poked they cause a nasty rash and give off dust that can cause respiratory problems. They are particularly toxic for children and animals.
If the caterpillar is stressed or threatened it can eject its hairs which act a little like harpoons and can penetrate or irritate any exposed skin. Dogs are particularly susceptible as they will pick up the hairs on their paws and then lick them as they start to itch. This then leads to the hairs being transferred on to the animal’s tongue and can result in itching, swelling, vomiting and even death.
What you should do if you find them
If you become aware that you have these caterpillars on an urbanisation then you should inform the community of owners and they should be removed. In some areas the council will remove them but where this isn’t the case you should engage a specialist. You should not attempt to move them yourself as it is a job for an expert.
If you do touch one and become itchy you should consult a doctor. The rashes can be very painful and irritating and can last for a few weeks.
If your pet is infected you can usually tell because there will be small white spots in the mouth and on the tongue and the animal will become distressed and possibly drool. If they remain untreated, animals can die as the tongue will swell and in some cases has to be cut or amputated. If you know your pet has been affected then you should go to the vets immediately, where they will probably be given a cortisone injection.
You should also be careful of any nests the caterpillars have left in the trees. These will also contain some of the hairs that the larvae have left behind. You should not try to cut down the nests or burn them yourself as the hairs can become airborn.
They are considered to be a real pest, a threat to the pine trees themselves and, of course, a danger to animals and humans. If you know of someone new to the area who may not be aware, it is worth warning them of the danger.
Some useful pictures of the different stages of the caterpillar can be found here: