We spotted these fellows this week, and whilst at the time I wasn’t 100% sure if they were the dangerous ones we decided to be cautious just in case.
And I am so glad we were. These are the caterpillar of the Pine Processionary Moth. Fascinating to observe but whatever you do don’t touch! The moths are harmless but the caterpillars have a rather nasty form of defence. Their tiny hairs, which drop off, are harmful to humans and mammals, and only a few birds are able to eat them. The hairs can cause anything from mild skin inflammation to a major allergic reaction.
Dogs have been known to lose their tongues after attempting to remove the hairs from their paws. So if you or your dog touch them the advice is to seek medical and/or veterinary help as fast as you can.
And it is not just the hairs which are the problem. The caterpillars are also an economic pest because of their diet and social behaviour. At the start of their development the caterpillars lay down a pheromone trail as they advance over the branches of the host tree to a feeding site. Other caterpillars will always choose to follow a trail, which results in large numbers congregating at feeding sites. They can completely defoliate trees if large quantities are present
Later on, when they are fully grown they abandon the pine trees in search of pupation sites. In early spring as many as three hundred caterpillars may seen travelling long distances looking for soft soil in which to bury themselves and form cocoons. It was this behaviour we were observed this week.
PS They nest in large numbers too, so maybe not advisable to camp under pine trees! And don’t forget to also avoid the Castor Oil plant!