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oak tree with acords

Are Oak Processionary Moths Back?

Oak processionary moths are a serious problem in London and the UK. These pests can cause health problems and have actually been declared a public health issue. In fact, the government has spent more than £40 million trying to eradicate them. This is definitely not your average London moth control problem.

What is the problem with these moths?

The reason why there are such concerns about these moths is due to the caterpillars’ bristles, which contain a defensive toxin. Fully grown caterpillars are covered with more than 70,000 of these bristles, and they frequently break off. When this happens, the bristles can come into contract with humans. This may cause a number of problems. For example, rashes, conjunctivitis and a number of other conditions are associated with these bristles. One of these conditions is asthma, which is why these moths are so dangerous.

oak processionary moths

These pests are tenacious, and despite the government’s best efforts, oak processionary moths are still around. This is according to a press release recently issued by the Forestry  Commission. In this press release, the public are urged to immediately report sightings of these pests.

How do you identify Oak processionary moths?

First of all, what you’re looking to identify are the oak processionary moths caterpillars. These are not like the typical types of moth that infest homes. They are black, and look like your standard caterpillar, except that they are covered in spiky white bristles.

Also, keep a look out for their nests. These are usually shaped like a dome but may also look like a tear drop. About the size of a tennis ball, the nests are white when new. Over time they take on a brown or discoloured shade.

moth nest on tree

Something else to watch out for is the behaviour of these pests. The caterpillars usually congregate together in large groups. As their name implies, they then move about in a large procession, travelling head to tail.

If you see a large group of black caterpillars with white bristles, then you’re probably dealing with oak processionary moths. In the event of a sighting, do you not touch or approach these caterpillars. Remember, their bristles are extremely dangerous, and cause many health problems.

The best thing to do is to immediately report a sighting. Contact your local council and inform them of the problem. Also, if you develop issues with your skin or eyes, or symptoms of asthma, make sure to seek medical attention as soon as possible.

Photos from Wikipedia copyright Kleuske and Falko Seyffarth, under license CC BY-SA 3.0 with thanks.


Sally has been writing on the subject of pest control for 4 years. She always carries out extensive and in depth research and always tries to bring you the most up to date, interesting topics.

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