This species, the processionary or processionary pine caterpillar ( Thaumetopoea pityocampa ) constitutes the second cause of destruction of Spanish pine forests, behind forest fires. It is a tremendously harmful pest with a presence throughout the peninsula and the Balearic Islands. The caterpillar, which belongs to the group of Lepidoptera, is found in parks, rural areas and forests where there are temperate pine forests, especially in southern Europe.
You have likely seen them at some point walking in a long line across the floor of a pine forest. This natural spectacle not only attracts the attention of humans, but also of dogs. The most curious canines may die trying to see what these odd-looking creatures taste like.
It is true that the caterpillars are always there, but only in the spring season (they anticipate due to the lack of rain and the warm temperatures) is when our paths cross. At the beginning of spring, rising temperatures triggers the burial instinct. The caterpillars come down from their nests (those whitish nets you see in the pines) and walk on the ground looking for a place to bury themselves and make a chrysalis from which they will then emerge in July in the form of moths. Some nests are small, but most nests are about the size of a grapefruit and contain approximately 300 caterpillars . The nests are generally located in the southern part of the tree (they are in a strategic position to obtain maximum sunlight) and there are usually several nests in the same tree. The caterpillars tend to disperse through trees at night to feed and then return to communal nests during the day to increase their heat and digest the food they have eaten.
Once they come down from the trees, they walk in procession (hence their name) led by a female, and it is clear that they would be easy prey for predators if they were not poisonous.
Dangerous to humans, deadly to dogs
That’s where the trouble begins for anyone who touches them. The caterpillars are covered in poisonous hairs impregnated with a toxin that, especially for dogs, is devastating. These hairs are even in the air around a heavily infested tree. Symptoms begin with the dog scratching its mouth, as if it wanted to poke something off the tongue with its claws while salivating profusely. At this point, you have to go to a vet as soon as possible because the pet can die.
The caterpillar causes various injuries to dogs. The symptoms are similar to those of an allergic reaction. The tongue, esophagus, and stomach swell. Eventually the dog cannot breathe and dies. In most cases, this does not happen by the swift action of a veterinarian, but the part of the animal’s tongue – or other area – that a caterpillar has touched, suffers necrosis. Some come to lose practically all the language.
Do not touch caterpillars or their nests under any circumstances
It is important that humans also do not touch the nests or go near them, as the hairs of the caterpillars constantly fall while they are in the trees and, of course, the nests are full of toxic hairs. These caterpillar hairs are stinging when in contact with the skin, causing allergic reactions, and pose a health risk, as they promote skin irritation in the form of a rash or rash that can appear on the arms, legs, neck, or torso and can last for several weeks. It can also lead to conjunctivitis and breathing problems.
There are people who even stepping on them has caused a reaction, since the hairs that get caught in the shoe can come into contact with the skin later.
The preferred tree of this caterpillar , which only eats pine needles, is the black pine ( Pinus nigra ), followed by the Canary Island pine (Pinus canariensis ), the Scots pine ( Pinus sylvestris ), the maritime pine ( Pinus pinaster ), the Aleppo pine ( Pinus halepensis) and stone pine ( Pinus pinea ).
How to end them -if necessary-
Taking into account that pesticides are one of the main causes of the marked loss of biodiversity with confirmed evidence in all the ecosystems of the planet, the use of fumigations with Diflubenzuron , for example, a highly polluting pesticide, is discouraged to fight against the pine processionary. There are other control methods by land that do not harm the environment or human health. For example, if the nests are very localized, the pockets can be eliminated by cutting them one by one and carrying out a controlled burning, always in compliance with current legislation.
