"My house is full of caterpillars": the headache for the residents of Turó de la Rovira

BarcelonaIn addition to the usual parade of noisy tourists who climb the anti-aircraft batteries every day in search of a good view of the city, residents of the Turó de la Rovira neighborhood in Barcelona are now dealing with the annoyance caused by another visitor: the pine processionary caterpillar. The hatching of these insects has become a major headache for the residents closest to the trees on the hill, who have seen their homes become infested with caterpillars. This is the case for Montse Jiménez, who lives on the upper section of Mühlberg Street and who, for the past few weeks, has had to close off the upper patio of her house due to the presence of these insects.

At first glance, you can see how the pine trees next to his terrace are covered in the typical nests these insects create to protect themselves from the cold. "The slightest breeze is enough to make them fall here," says Jiménez, showing the remains of one of these nests on the ground and a few caterpillars nearby. He explains that although the Parks and Gardens department has fumigated the tree, the spray cannons don't reach the upper parts of the tree and aren't entirely effective. Javi, a neighbor overhearing the conversation, agrees and explains that he's also had to stop hanging his laundry in the patio because it gets covered in caterpillars. Visitors to the bunkers during the first few weeks of the year have also suffered from the processionary caterpillar infestation. Laura and her family experienced it firsthand during the Christmas holidays. As she explains, they suddenly realized that one of her nephews was carrying six caterpillars, which caused him severe skin irritation and forced them to go to the pharmacy. "They were raining down from the trees," she explains, adding that the stairs leading to the top of Turó were littered with squashed insects.

The pine processionary caterpillar has hairs that can cause painful stinging if touched or if you get too close. It's more dangerous for dogs because if they eat or lick the caterpillars, the swelling of their tongues can cause them to suffocate. That's why, while Montse Jiménez points out the presence of caterpillars in various spots around her house, Yami and Shiro watch the conversation from a distance, waiting for their owner to let them go for a walk. "It worries me when they go up to the patio and swallow a caterpillar," she explains, adding that she also keeps them on their leashes when they walk in the mountains to avoid any unpleasant surprises.

Last week, the City Council intensified its efforts in the area to combat this pest. At the entrance to the bunkers from Mühlberg Street, a sign warns of the presence of pine processionary caterpillars. Municipal sources explain that, given the difficulty of accessing some of the pine tree canopies in the bunker area and Parc del Guinardó, they have opted to combine treatments with endotherapy for the most inaccessible pines and atomization for the rest. They also explain that during these weeks, accessible nests are being physically removed to minimize the number of caterpillars descending to the ground and "the potential nuisance they may cause."

The impact of the drought

On Tuesday, in fact, workers from the Parks and Gardens department could be seen in the area wearing white protective suits and gloves to avoid direct contact with the caterpillars, manually removing some of these nests. In a conversation with ARA, Marcos Clau, the coordinator of Pests and Diseases for Parks and Gardens, admitted that the processionary caterpillars have descended from the trees earlier this year, but stressed that this happens from time to time depending on weather conditions. Clau explained that the end of the drought may have contributed to the higher number of pine processionary caterpillars this year, and especially last year, compared to previous years when there was less rain. He also pointed out that they are more visible in Parc Guinardó because they haven't used chemical treatments for the last four years, as they have been conducting a biological control study of the pest using natural predators such as bats and birds. Now, however, they are carrying out endotherapy treatment—a highly effective injection into the trunk—on all the pine trees containing the processionary caterpillar's nests, which it builds to protect itself from the cold before descending the trunk in procession and burying itself to complete its metamorphosis into a moth. With this endotherapy treatment—used on pine trees near playgrounds, picnic tables, or dog parks because it is more effective than spraying and can last for two years inside the tree—Clau predicts that there will be far fewer pine processionary caterpillars next year. Clau points out that this treatment is "unthinkable" in forested areas due to its difficulty and cost, but since these are urban parks, the City Council is making an effort to minimize the nuisance caused by this pest, which, if left unchecked, can ultimately kill the pine trees.