Pine processionary caterpillars are back in Lebanon and pose a threat to the environment and public health. These insect pests can cause severe damage to trees and trigger allergic reactions in humans and animals.
The pine processionary caterpillar is a concern for the inhabitants of Lebanon’s wooded regions. Pine processionary (Thaumetopia wilkinsoni) has a significant impact on the environment and forest ecosystems. These insects feed on pine needles, which can be harmful to forests and gardens. TTrees with processionary caterpillars can be weakened, which can affect their growth and make them more vulnerable to other diseases or pests.In addition, when caterpillars leave one tree to colonize another, they often leave behind a sticky white substance called a “nest” which can cover branches and leaves, disrupting photosynthesis and tree growth.
Nabil Nemer, a pine processionary entomologist and professor at the University of the Holy Spirit of Kaslik (USEK), said: “The pine processionary cannot be considered invasive since it is indigenous, however, it can cause several problems. It causes allergic reactions in terms of health, and it is responsible for the devastation of forests.”
“Nemer explains that this caterpillar is typically found in moderate numbers in low-lying areas below 800 meters. “Today the processionary caterpillar is found at altitudes of up to 1,500 meters. This is because global warming makes temperatures more favorable for its development. In Europe, it is considered a sign of global warming. In cold winters, most of these caterpillars die, which helps keep populations under control with predatory birds. However, winter temperatures have become milder in the last few years, which has made it easier for the species to survive. Overpopulation could lead the caterpillars, which normally feed on wild pines (Pinus brutia), to prey on laricio pines (Pinus pinea) to feed on. This substitution ability is passed on to their offspring, which is a serious problem.
“Nevertheless, pine processionary caterpillars are important to the environment. They eat only tree leaves. Although this may appear to be a nuisance, it helps regulate tree growth and nutrients flow in the soil. Therefore, the complete elimination of processionary caterpillars can have negative effects on the environment.
Be careful of stinging hairs
The processionary caterpillars stinging hairs pose a major threat. In fact, they easily detach and float in the air, causing severe allergic reactions in humans and animals. The most common symptoms include rashes, itching, pain, nausea, and vomiting. “The itching caused by these hairs is treated with soap and water, according to Roland Tomb, a dermatologist and dean of the Saint Joseph University Faculty of Medicine. “In cases of severe allergic reactions, antihistamines will be administered on medical advice or cortisone-based creams will be used to relieve pain and stop the inflammatory reaction.”
It is therefore advisable to take the necessary measures to avoid contact with caterpillars and their stinging hairs, especially to protect children who may want to touch them out of curiosity. Pets can be affected as well, especially dogs that enjoy running in the woods.
Getting rid of processionary caterpillars
There are several ways to get rid of processionary caterpillars. The most effective method is to cut the infested branches and burn them immediately. One must be careful, as the stinging hairs may also fall off from the branches and float in the air. It iIt is recommended that trees be inspected regularly, especially during the winter when caterpillars gather in colonies to protect themselves from the cold.
Birdhouses are another way to attract pine processionary predators, such as the great tit (Parus major) or the Eurasian jay (Garrulus glandarius)
Pesticides can also be used to kill the caterpillars. According to Abbas Hajj Hassan, Minister of Agriculture, the Lebanese Ministry of Agriculture chose this solution because it’s important to get rid of this caterpillar quickly. Since pesticides can affect other insects and animals, the ministry only resorts to this method in cases of extreme urgency in the most affected areas. It is important to use integrated management strategies to keep processionary caterpillars from harming the environment and public health.
Another solution would be to use plants as natural repellents, including eucalyptus, oleander, thyme, boxwood, pyrethrum, tansy, common juniper, sycamore maple, ivy, rosemary, and Leyland cypress.
Contrary to some beliefs, it is not recommended to shoot at processionary caterpillar nests, as this will cause a massive release of their stinging hairs, which will persist in the air for several months.
Furthermore, public awareness is also essential. Schools and local communities can play an essential role by organizing workshops and conferences.