Processionary Caterpillar – Protect Your Pets

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Processionary caterpillars, known scientifically as Thaumetopoea pityocampa, are fascinating creatures at first glance, but behind their harmless appearance lurks a potentially lethal danger for our four-legged friends.

processionary caterpillar track on wooden plank floor

Originally from southern Europe, these creatures have a peculiar life cycle that can pose a serious risk to pets, especially cats and dogs.

The Life Cycle of the Processionary Caterpillar

processionary caterpillar nest in a pine tree

The life cycle of the processionary caterpillar begins when the adult female moths lay their eggs at the ends of tree branches, usually pine trees. After a few weeks, the caterpillars emerge from these eggs, feeding on leaves and rapidly growing in size. During the feeding period, these urticant creatures weave characteristic webs in the shape of nests, where they take shelter during the coldest months of the year.

As spring approaches, the now mature caterpillars leave their nests in search of soft soil to burrow in and begin the pupal stage. After a few weeks in this phase, the adult moths emerge, restarting the cycle by laying their eggs in the surrounding trees.

The Danger to Pets

Although the processionary caterpillar may go unnoticed by many, its presence poses a serious risk to pets. The hair that covers their bodies contains a toxic substance that can cause serious allergic reactions and even death in dogs and cats.

the stinging hairs of the processionary caterpillar in detail

The animals, often curious, can be attracted to the caterpillars’ nests or even to the creatures themselves while they are on the ground. By sniffing or licking the caterpillars, their faces and tongues can come into contact with the urticant bristles, triggering a series of adverse symptoms. These include swelling, irritation, vomiting, difficulty breathing, necrosis and, in extreme cases, anaphylactic shock.

processionary caterpillar nest in a pine tree

Prevention and Care Measures

Here are some preventative measures that can help you avoid contact with these creatures effectively:

  1. Avoid infested areas: Knowing the areas where processionary caterpillars are common can help you avoid exposure. Avoid walking or letting your pets loose in places where these creatures are known to inhabit, such as pine forests or wooded areas.
  2. Keep pets under control: During outdoor walks, keep your pets under close supervision and control. Use leashes or collars to ensure they don’t go near potentially dangerous areas.
  3. Educate yourself on the signs of infestation: Learn to recognize the signs of the presence of processionary caterpillars, such as the presence of nests in trees or the observation of the caterpillars themselves on the ground. Look out for these signs when exploring natural areas.
  4. Remove nests when possible: If you spot processionary caterpillar nests in trees near your property, consider contacting pest control professionals or vegetation management services to remove the nests safely and properly.
  5. Protect the trees: There are preventative measures that can be taken to protect trees from infestation by processionary caterpillars. Consult a gardening or pest control specialist for advice on chemical or physical treatments that can be applied to prevent the presence of these creatures.

In the event of suspected exposure to the processionary caterpillar, it is essential to seek veterinary assistance immediately. Symptoms can develop rapidly and require urgent treatment to avoid serious complications.

How to Deal with the Processionary Caterpillar

If you find processionary caterpillars on the ground, it is important to approach the situation with extreme caution because of the danger they pose due to their stinging bristles.

foot with sneakers about to crush a processionary's path
Evite esmagar as lagartas. pode libertar pelos urticantes para o ar

The ideal is to avoid close proximity as much as possible, but in case that’s not possible, here are some guidelines on how to handle them safely:

  1. Avoid direct contact: Simple handling can cause the release of stinging hairs into the air, which can land on the skin, eyes or be inhaled, so be extremely careful. Never touch processionary caterpillars with bare hands. Urticant hairs can cause skin irritation and severe allergic reactions. Wear thick gloves and appropriate protection when handling these creatures.
  2. Use tools: If you need to remove caterpillars from the ground, use a shovel, tweezers or another long tool to handle them. This will help keep a safe distance between you and the caterpillars, minimizing the risk of exposure to the urticant hairs.
  3. Avoid crushing the caterpillars: Try to avoid crushing processionary caterpillars, as this can release their urticant bristles, increasing the risk of exposure. Instead, use removal methods that don’t involve crushing, such as putting them in a closed container.
  4. Dispose of carefully: After removing the caterpillars from the site, place them in a sealed container or plastic bag and dispose of them properly. Make sure you seal the container well to prevent the caterpillars from escaping.
  5. Cleaning: After handling processionary caterpillars or coming into contact with areas where they were present, wash your hands and other exposed parts of your skin thoroughly with soap and water. This will help to remove any stinging bristles that may have been left on the skin.


In short, although the life cycle of the processionary caterpillar may seem like just an inofensive critter, its potential to cause harm to pets is a serious concern. Staying alert to the presence of these creatures and adopting appropriate preventive measures are essential steps to ensure the safety and well-being of our furry friends.

By following these safe handling guidelines, you can deal with processionary caterpillars effectively, protecting yourself and others from possible harm caused by the creatures’ stinging bristles.

If you have any questions about this or other topics, please contact us.

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