Processionary Caterpillars

Thaumetopoea pityocampa Schiffermuller

Processionary Caterpillars are so called because they form processions, nose to tail, as they leave the nest prior to changing into moths. They are found in all Mediterranean climatic areas, ranging from Portugal in the West through to the Adriatic and beyond in the East. The “nests” are fist sized or larger balls of spun filaments, usually lodged in fairly high branches of pine trees.

Processionary Caterpillar Nest in Pine Tree

The months from October through to March and April see the time when the caterpillars descend from the cocoon nests and they will then form “processions” in search of soft, warm earth in which to pupate. There can be hundreds of caterpillars nose to tail, winding along roadways, paths, grass, whatever. The caterpillars have poisonous and irritant brittle hairs on their bodies, and are a mottled dull brown with faded yellowish splotches.

In adults these hairs will cause severe skin irritations, and occasionally anaphylactic shock, closure of airways leading to death, and obviously requiring immediate medical treatment. In children, (who are more inquisitive about the processions and may handle the caterpillars then transfer the fingers and hairs to the mouth etc) the effects can be more immediately severe and will almost always require immediate professional medical aid. Similarly, older people with less resistance can also be quickly affected. Golfers, tennis players, footballers and bowlers (petanque and boules) should be careful NOT to handle a ball that has gone through a procession, golfers should check local rules, some courses permit substitutions. Golf, Tennis, boules and Footballs should be cleaned with disposable cloths which should then be burned as a means of disposal.

For pets, dogs and cats, the problem is that the caterpillars have a bittersweet smell and taste, and both dogs and cats will try to eat them. The results are almost certainly fatal, as little as three or four will kill a medium sized dog, and one may produce death in a cat. The reaction to the poison also causes necrosis of the tongue, and by the time the owner notices the problem, it is usually too late for veterinary treatment to do much except ease suffering.

Do not brush a procession away as this can cause more problems than it solves, spreading the irritation-producing hairs and thus the risk of poisoning actually becomes higher as a result.

POISONOUS: do not handle!

The Portuguese for caterpillar is Lagarta (not to be confused with lagarto – lizard)