Oak Processionary Moth caterpillars
Although moths play an essential role in plant pollination, provide food for many species of resident and migrant birds, and contribute to Jersey's rich biodiversity, the Oak Processionary Moth can be dangerous to human and animal health while it is a caterpillar.
Oak Processionary Moth caterpillars
In May, June and July, their caterpillars (larvae) collectively build a silken nest, covered in their toxic hairs, and they shed hairs into the tree they are feeding in, making the entire area hazardous.
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An Oak Porcessionary Moth caterpillars' nest
The hairs can be blown by the wind, and they accumulate in the caterpillars' nests which can fall to the ground. They can stick to trunks, branches, grass and clothing as well as tree surgeons', forestry and ground-care workers' equipment, such as ropes.
It becomes harmless when the insect pupates into a moth form.
Risks to human and animal health
Contact with the toxic caterpillar hairs can cause:
- Skin irritation
- Allergic reaction
- Intense itchiness
- Painful rashes
- Eye problems
- Sore throat
- Breathing difficulties
Anyone with a severe reaction or who is uncertain what has caused their rash should consult their GP.
Vulnerable groups
The groups most vulnerable to the caterpillar hairs are:
- curious children
- curious pets
- people who work on or close to oak trees
- anyone spending time close to infested trees
- anyone grazing and browsing livestock and wild animals
How to minimise the risk
To minimise risk:
| Avoid or minimise time spent under or downwind of infested oak trees | Touch or approach nests or caterpillars |
| Teach children not to touch or approach the nests or caterpillars | Let children or animals touch or approach nests or caterpillars |
| Train or restrain pets from touching or approaching them | Try removing nests or caterpillars yourself |
| Keep horses and livestock a safe distance from infested oak trees – cordoning off infested trees, or stabling can help |
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| See a pharmacist for relief from skin or eye irritations after suspected OPM contact |
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| See a doctor if you think you or someone in your care has had a serious allergic reaction - tell the doctor you suspect OPM contact |
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| Consult a veterinary surgeon if you think your pet or livestock has been seriously affected - tell the vet you suspect OPM contact |
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| If you work on or near oak trees in the affected areas, for example, as a tree surgeon or forestry, landscaping or ground-care worker, wear full protective clothing |
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How to spot them and what to do
Report any sightings, with as much detail as possible on their precise location, by
emailing the Environment Department.
Do not touch the caterpillars, their trails or their nests.
Report nests even if you do not see any caterpillars, because nests are a useful sign that the pest is in the area.
Signs that they are Oak Processionary Moth caterpillars include:
- bare oak trees - the caterpillars will nest in oak trees and feed on the leaves, large populations of them will strip whole oak trees bare
- cream to brown to black fibrous or webbing like structures on the trunks, branches and in forks of branches – these contain the caterpillars and the hairs and should not be approached or interfered with
- seen processing across the ground between oak trees
- seen feeding on sweet chestnut, hazel, beech, birch and hornbeam
- caterpillars cluster together while feeding or moving from place to place
- very long, white hairs
- a grey body and dark head, older caterpillars have a central dark stripe with paler lines down each side
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