Rising temperatures bring forward arrival of pine processionary caterpillars

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This insect, which is easily identified by its processional movement, releases thousands of stinging hairs that are highly irritating.

Raquel Merino

Málaga

Friday, 27 February 2026, 12:58

Rising temperatures are bringing forward the fall of the pine processionary caterpillars, thus extending the risk for dogs and cats in pine forests and urban garden areas.

The Madrid veterinary hospital centre (Grupo Iskaypet) has reported that in recent weeks they have been treating many cases due to contact with this type of caterpillar. The reactions it can cause range from severe inflammation to necrosis of the tongue and mucous membranes, eye lesions and even respiratory problems if action is not taken quickly.

The technical director of the hospital, Rubén Duque, explained that "the processionary is no longer just a late spring problem; we are seeing cases earlier and for longer". As he pointed out, the descent of the pine processionary caterpillars, which usually occur in March and April, is happening earlier due to milder winters. This makes it necessary to reinforce prevention from the end of winter and to maintain active surveillance for several weeks.

The caterpillar, which is easily identifiable by its processional movement, releases thousands of highly irritating stinging hairs. Simple contact with the snout or tongue can trigger severe inflammation within minutes, with a risk of necrosis if immediate intervention is not carried out. Some of the symptoms by which a reaction caused by contact with this caterpillar can be identified include intense hypersalivation, swelling of the lips and tongue, acute pain and even breathing difficulties. Eye injuries and severe skin reactions may also occur. “Prompt treatment is crucial to prevent permanent after-effects,” Duque added.

Furthermore, it should be noted that the risk of contact is not only with live caterpillars, but that the stinging hairs of the pine processionary retain their irritant capacity even when the insect has died or when the remains of the nest have fallen to the ground. These tiny filaments can remain active for months and disperse through the air, which explains reactions in animals that have not had visible contact with them, as reported by the ministry for ecological transition and the demographic challenge.

Seven key recommendations

The Madrid veterinary hospital proposes seven practical recommendations to help reduce exposure and to act correctly in the event of a suspected contact.

- Avoid areas with pine trees in times of risk.

- In areas where caterpillars may be present, dogs should be kept on a leash to limit the possibility of them approaching, sniffing or attempting to interact with caterpillars.

- Do not allow them to sniff or lick debris on the ground, even when caterpillars are not clearly distinguishable, as the stinging hairs may remain active and scattered.

- After each walk in risk areas, it is advisable to check paws and muzzle for debris and to act quickly if a reaction is observed.

- Never handle caterpillars or their nests. In addition to endangering the animal, direct contact also poses a risk to humans.

- If, despite all precautions, contact is suspected, the affected area should be washed immediately with plenty of lukewarm water, without rubbing, in order to wash away the stinging hairs without breaking them or encouraging their penetration.

- Any symptoms, no matter how mild, should be reported to a veterinary clinic as soon as possible. "The margin for action is very short. In cases of contact with processionnaires, every minute counts," Duque concluded.