ProcessionáriaGeneral features
This is an insect that defoliates pine and cedar trees, under the scientific name Thaumetopoea pityocampa. As such, it leads to a weakening of the trees and depending on the degree of attack it may cause their death. The attacks of this pest vary in intensity according to its population levels, which are strongly dependent on climatic conditions.

The biological cycle of the Processionary Caterpillar

Like all insects, it develops through the following stages:

– Egg
– Caterpillar
– Pupa or chrysalis (cocoon)
– Adult insect (butterfly)

The biological cycle of the Processionary Caterpillar is generally completed in one year, with two phases: an aerial one in the pine tree crown and another underground, in the soil. The 1st and 2nd growth stages, in the crown, normally occur in autumn (beginning mid-September/late October). Young caterpillars live in temporary nests, which are abandoned until a definitive nest is formed (winter nest), where they live in a colony and protect themselves from low temperatures. Treatments

Chemical treatments are very effective at this stage. Normally, two groups of products of low toxicity and innocuous for the environment are used:

Diflubenzuron – These are growth inhibitors, the most widely used being Dimilin;
Microbiological insecticides – based on Bacillus thurigiensis.

From the 3rd stage onwards, when they become a health risk, they have stinging hairs, which cause allergies on the skin, the eyeball and the breathing system. These allergies are always very unpleasant and can lead to serious consequences, depending on the sensitivity of the affected victim. In the case of advanced caterpillar infestations between the 3rd and 5th stadium (normally occurs in the winter period), it should be taken into account that the insects are in the active growth phase. They build their nests during this period – taking on the appearance of a silk ball – and maintain night feeding habits, remaining in the nest during the day (the nest functions as a thermal accumulator).

A threat to public health

In terms of public health, the Processionary Caterpillar can be a serious concern, especially in high population years and close to inhabited areas.

The severity of infestation varies according to its population levels, which are strongly influenced by climatic conditions. In terms of wood production, there is a decrease in tree growth during the period when trees are defoliated. Besides causing this damage to trees, the pine processionary can also cause serious public health issues. Due to the urticating properties of its hairs, it causes skin, eye and breathing allergies in humans and can lead to the same in domestic animals. Hospital assistance is often required in case of physical contact or merely close contact with the processionary.