May 8, 2025
The pine processionary caterpillar (Thaumetopoea pityocampa) is a lepidopteran insect that is causing concern in many regions of Spain and other Mediterranean countries due to the risks it poses to human health and, especially, to that of pets.
Pet owners know that with the arrival of spring, they must be wary of pine processionary caterpillars, as their attacks can be fatal for animals. In fact, they don't even need to be touched: when they feel threatened, they can launch their stinging hairs like darts. There are approximately 500,000 of them, which cover their bodies and contain a toxin called thaumatopin. These hairs can cause anything from a simple sting to intense allergic reactions and even death..
What to do if we are affected
People at greatest risk of severe illness from a processionary caterpillar attack are those with respiratory or heart problems. They should seek medical attention immediately and avoid scratching or rubbing the affected skin, as this could spread the condition. They should also avoid touching their eyes, ears, mouth, or nose with their hands.
One way to relieve itching, for both humans and animals, is to pour water on the skin, but do not rub or scratch it. Pets are at risk of death, especially if they swallow a caterpillar. In this case, action should be taken with extreme urgency and a veterinarian should be consulted, as the animal can die in just one or two hours.
The best advice to avoid problems is to avoid walking dogs or other pets in areas with pine trees.
In addition to everything mentioned above, the processionary caterpillar defoliates trees, and if the population is very high, it can affect the entire leaf mass.
Life cycle of the pine processionary caterpillar
The pine processionary moth goes through different stages in its life cycle.
Adult butterflies emerge between June and September, depending on weather conditions..
After mating, the females lay their eggs on the pine needles, from which larvae hatch and begin feeding on the leaves of the host tree. These larvae, which cause the most damage, undergo several molts and develop stinging hairs.s.
When they reach their final larval stage, the caterpillars descend to the ground in single-file formation, a characteristic behavior that has earned them their common name.
In the soil, they excavate galleries where they bury themselves to complete their metamorphosis and emerge months later as adult butterflies.
But this caterpillar has another side: despite its harmful effects, it also plays an important ecological role in forest ecosystems..
Eradication is not recommended
Since the total eradication of the pine processionary caterpillar is neither viable nor ecologically advisable, sustainable management strategies are required to minimize its negative impacts without altering the natural balance of ecosystems.
The pine processionary caterpillar is eaten by numerous animals throughout all stages of its life cycle, which have developed adaptations to consume it without being affected by its stinging hairs. The eggs are eaten by ants and wasps; the early caterpillars by insectivorous birds such as the great tit, the common blue tit, and the cuckoo; the advanced caterpillars by birds such as the blackbird, the hoopoe, and the crow; and the moths by bats and dormice.
Furthermore, their metamorphic remains provide nutrients to the soil and contribute to the recycling of organic matter in forests.
Furthermore, their presence in certain environments indicates the health of forests and their ecological balance. Under natural conditions, the processionary caterpillar is part of the forest dynamic, regulating the density of young pines and preventing their excessive proliferation, which in turn can prevent forest fires by reducing the accumulation of flammable biomass.