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I captured this photograph for The Readers' Photos of La Vanguardia these first days of February on the Carretera de las Aguas, in Barcelona. It is a danger for walkers and dogs, without a doubt.
The caterpillars (larvae) are covered with stinging hairs that break off and float in the air, which can cause irritation to the ears, nose and throat in humans, as well as intense allergic reactions. The substance that gives it this stinging capacity is a heat-labile toxin called Thaumatopine.
The processionary season used to be exclusively in the months of March and April, but climate change has softened winter temperatures.
Especially, this winter is being very spring-like, so it is already possible to see the rows of pine processionary looking for places to bury themselves to begin their metamorphosis process. It is bad news for the trees of Collserola.
The processionary is considered a forest pest, since it seriously damages the foliage, weakening the trees and exposing them to other diseases. It is the most important defoliating insect in pine forests in Spain.
The processionary can feed on all species of the genera Pinus, Cedrus and Abies, but they prefer pine trees. In this case it can be seen on the Carretera de las Aguas. It is easily accessible, either by public or private transport, and leads to the Collserola Natural Park, a large green lung in the Barcelona area.
It owes its name to the old route of a water pipeline, of which the horizontal layout is maintained. With its almost 10 kilometers in length and a maximum elevation of 450 meters, it is one of the most popular trails among Barcelonans who love cycling and walking.
