Why are Oak Processionary Moths Dangerous?

What are Oak Processionary Moths? Oak Processionary Moths are a species of moth, that before metamorphizing into moths are caterpillars. And it is this stage of being a caterpillar that is important for us. Because at the stage of being a caterpillar the Oak processionary moth are harmful to not only humans but to oak trees too.

The Oak Processionary Moth were accidently introduced into the UK in 2005, no one is entirely sure how this happened. But its quite likely there were Oak Moth eggs on vegetation which had been imported. At the moment most of these caterpillars are distributed in London. As it stands around £37 million has been spent by the UK government to control the population.

Why are Oak Processionary Moths Dangerous? – Oak Trees

The caterpillars are mainly an issue for oak trees, because they feed on oak tree leaves. This in itself is not normally enough to kill the oak trees, it does however greatly weakened the trees. Meaning they are left vulnerable to not only other diseases, but other things like drought. As I’m sure you can see this is not good! Oak trees being a vital part of the ecosystem,  but unfortunately this is not the only frustration Oak Processionary Moths cause us.


Why are Oak Processionary Moths Dangerous? – Humans

The caterpillars produce hairs which cause irritation to humans and animals. The effects of these hairs include: itchy rashes, sore eyes, uncomfortable throats and breathing difficulties. None of us want any of these symptoms! So how do we deal with these caterpillars?


Well, firsts its important that we are able to identify them. This means we know both what the caterpillar looks like, but also what their nests look like. The caterpillar is quite a distinct looking fellow,  it has a grey body with a dark head – all of which is covered by long white hairs. Your probably only going to be seeing these in months May to July. So if you come across something matching this description in December your probably alright!

Nests are slightly less obvious, but still have some important identifying features. For example they are made out of a sort of white webbing, but are also typically surrounded by white tendrils of the same material. Furthermore they tend only to be on trees, so your fences and homes are safe from these!

What to do

If you think you have found Oak Processionary Moths, leave them alone and contact Shawyers