grey and white cat itching in grass

Cats are more likely to come into contact with the dangerous caterpillar in the springtime

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Cats and the danger of processionary oak caterpillars

By Justine Seraphin Country Manager

Updated on the

While you may be overjoyed with the arrival of Spring, keep in mind that the season brings a lot of new dangers for our pets - the processionary caterpillar is one of them.

Processionary caterpillars are the larval stage of a type of moth. Processionary caterpillars build nests in trees at the end of autumn and spend the winter inside a silk cocoon. Then, in the spring, as temperatures start to rise, they migrate down from the trees and into the ground, where they can complete their transformation into fully-fledged chrysalis. They are called “processionary” due to the way in which they travel in single file.

Processionary caterpillars can be dangerous, not only to humans, but also to our pets! Here’s everything you need to know about these pesky critters.

Are there processionary caterpillars in the UK?

There are two types of processionary caterpillars: pine and oak. For now, only Oak Processionary Moth (OPM) caterpillars have been spotted in the UK. They are not native to the country and were accidentally imported from mainland Europe during tree-planting schemes.

The presence of OPM caterpillars have been reported since 2006 in the following areas: London, Berkshire, Buckinghamshire, Essex, Hertfordshire, and Surrey. 

Are caterpillars dangerous to cats?

While most butterflies and moths pose no danger to cats, their caterpillar larval stage can be extremely dangerous. 

Many caterpillars are covered in urticating hairs which they use as a defense mechanism when they feel threatened or attacked. While some only cause light irritations, others, such as the processionary caterpillar, can cause much more serious reactions. 

What do processionary caterpillars do?

If your cat comes into contact with a processionary caterpillar, the caterpillar may feel threatened and release their urticating hairs which will then hook into your pet’s skin and/or surfaces of other organs, resulting in the release of a highly dangerous toxin. 

Contact with the caterpillar is more likely in spring when they travel from their nests in trees down to the ground. However, since their hairs are volatile, they can easily attach to your pet’s skin or fur by simply being transported through the air. 

Symptoms of contact with a processionary caterpillar:

  • Contact with the skin: Rash, itching, and swelling
  • Contact with the eyes: Inflammation of the conjunctiva and cornea. If left untreated, this can cause corneal ulcers and even loss of sight.
  • Contact with the mouth: Inflammation around the mouth and necrosis of the tongue. If left untreated, this can cause some parts of the tongue to fall off. 
  • Ingestion: Salivation, fever, vomiting, inflammation of the stomach and digestive tract. 

What should I do if my cat has been in contact with a processionary caterpillar?

If you find a caterpillar on your cat’s coat, put on a pair of rubber gloves or use a thick wad of tissues to remove it. You should then rinse the affected area without rubbing it, and take your cat to the vet as soon as possible. Your cat may be prescribed a cortisone treatment. 

Due to the volatile nature of OPM caterpillar hairs, it’s very important to keep a close eye on your pet during springtime. As cats often groom themselves, they’re even more at risk of ingesting hairs that may have attached to their coat or skin. Brush your cat frequently and try to avoid letting them out in areas where you know the caterpillar is present.

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