Oak Processionary Moth

The caterpillar of the oak processionary moth is highly poisonous, and is causing a severe threat to our oak trees.

They are potentially toxic to humans, pets, livestock and other animals and should be reported to your local council.

Tremendous efforts have been made to cull the oak processionary moth without success.

Unfortunately, the oak processionary moth also has very little in the way of any natural predators in Great Britain.

Having first being identified back in 2006 in Richmond (who have, incidentally, spent £200,000 plus trying to eradicate them).

They have now managed to establish themselves successfully in several parts of London.

In particular the boroughs of Richmond, Wandsworth, Hounslow, Ealing and Brent have seen the worst of it.

Due to the unsuccessful culling attempts, experts have been left with no other option but to contain them.

Obviously as the only method of control to try and prevent the moth from spreading to other areas.

Oak tree species affected include English, Turkey, and Sessile.


Oak Processionary Moth Description & Background Information

The oak processionary moth is native to central and southern Europe.

It is thought to be imported from the continent back in 2006, most probably from eggs laid on oak trees.

The caterpillars have a brown body and a dark coloured head when first hatched. As they start to grow, this colour lightens.

They are also covered in thousands of tiny hairs. Along with very noticeable, long white hairs making for a marked contrast.

The hairs contain a toxin called thaumetopoein which may cause an irritating rash on the skin.

In extreme cases, they can also cause eye problems, sore throats and even difficulties in breathing.

This is particularly true to people with breathing problems such as asthma, so do avoid even touching one.

The hairs are shed as a defence mechanism. The oak trees then becoming covered in these tiny unnoticeable hairs.

Anyone touching the trees poses a potential risk from the hairs and they are also easily dispersed by the wind.

Of course, you do not need to be that close to an oak tree to be at risk of coming into contact with the hairs, including inhaling them.

Caterpillars also cause untold damage to oak trees, feeding rampantly on their foliage thereby causing devastating defoliation.

This, in turn, weakens the trees thus making them vulnerable to becoming infected with various other diseases and even possible death.


Oak Processionary Moth: Identifying a Moth or Nest

Oak processionary moth caterpillars can easily be recognised in about early spring to early summer when they start moving around in a nose to tail procession (hence the name).

You may also notice their nests on the branches and trunks of oak trees, which usually start to appear in early summer.

When newly built they are white and silky, along with white silky trails to be found in the trunk and branches, although they soon become discoloured making them harder to see.

As for recognising the adult moth, they are a very undistinctive brown colour and look just like any other harmless moth.

You may be able to identify them better when they start to become active from the middle to late summer.

Hovering around oak trees, they look for suitable places on branches and twigs where they can lay their eggs.

It should be noted that the oak processionary moth tends to contain itself to only oak trees (as the name suggests).

If you have oak trees in your garden, it is important that you keep an eye on your tree/s for signs of the caterpillars and their nests.

Unlike other species of caterpillar which can often be seen on walls, fences, trees, bushes and other structures, they are generally only found on oak trees.

Although, having said that, when large populations completely defoliate oak trees in their local vicinity they will start feeding on other trees.

This happens when they run out of oak foliage to eat and they have now been seen on birch, beech, hazel, hornbeam and sweet chestnut trees.

Any nests seen in the leaves are almost certainly not the oak processionary moth but will be those of another species of moth.


Report a Sighting to the Council

If you see a nest under no circumstances should you touch or try to remove it yourself.

Apart from causing a potential health risk to yourself or others, you may also cause the problem to be spread.

Report your sighting of these caterpillars to your local council, who may also advise that you should report your sighting to the forestry commission.

The councils of all infected areas, along with the forestry commission are all working very hard to keep the oak processionary moth under control.

Your local council may also be able to provide you with telephone numbers of suitable pest control operators that can remove the nests for you.

Should you see one in a public place, then please do report it immediately to your local authority.


Calling a Professional Arborist

Should you be unfortunate enough to spot any oak processionary moth caterpillars or their nests in your oak trees, then keep well away from the infected tree or trees.

These nests need to be removed and destroyed by qualified professionals such as a qualified arborist.

They are used to dealing with them as they come across them when pruning oak trees and may offer nest removal as one of their services.

In any event, they will certainly be able to advise you as to what steps you need to take.


Article was written by Karen Arnold.

Edited by Conner D on 01/07/2019.

Article Source: https://www.graftingardeners.co.uk/oak-processionary-moth/


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