Warnings about caterpillars in the East of England that cause breathing difficulties and rashes have been issued by the Forestry Commission.

East Anglian Daily Times: Oak Processionary Moths (OPM) are most prevalent between May and July and can cause breathing difficulties and skin irriation to those that come into contact with them Picture: KELUSKEOak Processionary Moths (OPM) are most prevalent between May and July and can cause breathing difficulties and skin irriation to those that come into contact with them Picture: KELUSKE (Image: Archant)

Oak Processionary Moths (OPM) were first identified in London in 2006. Since then, reports of the bug have been made in several counties surrounding the capital including Essex, as well as less frequent cases in Suffolk and some as far flung as Scotland.

They get their name from their distinctive movements on a tree, forming a large, nose-to-tail procession.

The moth is currently in the caterpillar stage of its life cycle, before pupating and becoming a moth in July. The caterpillars feed on oak leaves and have black heads and bodies covered in long white hairs.

While the moth is harmless, those that come into contact with the caterpillar’s hairs can experience itchy rashes, irritation to the throat and eyes and, in some cases, breathing difficulties.

East Anglian Daily Times: Contact with the caterpillars hairs can cause skin irritation, like this rash, as well as breathing difficulties Picture: HENRY KUPPENContact with the caterpillars hairs can cause skin irritation, like this rash, as well as breathing difficulties Picture: HENRY KUPPEN (Image: Archant)

The Forestry Commission advises that people should not touch them under any circumstances.

Forestry Commission director for south-east England, Craig Harrison, said: “Green spaces with trees are proving particularly valuable for visitors of woodlands, who are exercising whilst practising social distancing this spring.

“Controlling OPM will help protect oak tree health and ensure continued enjoyment of parks and woodland by reducing the impact of OPM caterpillars to human health.”

When are the caterpillars most dangerous?

Advice from the Forestry Commission says the greatest period of risk is May to July, when the caterpillars emerge and feed before pupating into adult moths.

However, caterpillars and nests should not be touched at any time.

The caterpillars feed on oak leaves, which can leave the trees vulnerable to other pests and diseases and drought.

What do their nests look like?

Nests are typically dome or teardrop-shaped, averaging the size of a tennis ball.

They are white when fresh, typically in April, but soon become discoloured and brown.

• Any sightings should be reported to the Forestry Commission by emailing opm@forestrycommission.gov.uk or calling 0300 067 4442.

• Anyone pruning or felling oak trees in the affected areas should contact Forestry Commission England’s Plant Health Forestry Team beforehand on opm@forestrycommission.gov.uk or 0300 067 4442 for advice about safe removal of the material.

• Have you seen the caterpillars on oak trees where you live? Let us know by emailing newsroom@archant.co.uk