The Forestry Commission has put out a warning after a rise in sightings of 'poisonous caterpillars'.

A number of people across SE London have recently taken to social media to alert others to large groups of Oak Processionary Moths (OPM).

So far they have been spotted in Sydenham and several parks in Bexley.

For humans, the tiny hairs that cover the caterpillars bodies can cause skin and eye irritations, sore throats and breathing difficulties, they can also affect dogs too.

Some people have also been violently sick after coming in contact with the insect and some have suffered toxic shock.

READ MORE: Council plans to eradicate toxic caterpillars from Bexley parks

The Forestry Commission says that these OPM caterpillars feed on oak leaves and large populations can strip trees bare.

OPM caterpillars are recognised by their habit of moving about in late spring and early summer in nose-to-tail processions.

If you are worried about your trees, look out for distinctive white, silken webbing nets on trunks and branches.

What do they look like?

The OPM caterpillars have very long, white hairs (each caterpillar has around 65,000) which shed and can be active for up to five years.

How do you stay safe around such creepy crawlies?

Do not touch or approach nests or caterpillars

Do not let children touch or approach nests or caterpillars

Do not let animals touch or approach nests or caterpillars; or try removing nests or caterpillars yourself

READ MORE: Wild Things: Impact of chopping trees - and good news about bees

What should I do if I see some?

If you think you have found a next of OPM caterpillars then you should email the Forestry Commission on and they will begin treating the affected areas.

People in London and the South East of England are being reminded to report sightings of Oak Processionary Moth (OPM) caterpillars, which could be damaging oak trees in their area.

Any sightings should be reported to the Forestry Commission via its Tree Alert online form. Alternatively, people can email or call 0300 067 4442.

The Forestry Commission, councils and land managers have an annual programme in place to tackle the pest, which affects certain part of the country in the Spring.

How to identify OPM

Nests are typically dome or teardrop-shaped, averaging the size of a tennis ball. They are white when fresh, but soon become discoloured and brown. The caterpillars have black heads and bodies covered in long white hairs which contain proteins which can cause itchy rashes, eye and throat irritations.

The greatest risk period is May to July, when the caterpillars’ emerge and feed before pupating into adult moths, but 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.

Craig Harrison, the Forestry Commission’s South-East England Director, said: "The public and those working in green spaces such as tree surgeons and gardeners can help by reporting any suspected OPM sightings.

"However, they should not touch the caterpillars or nests themselves; removal is most safely done by specially trained and equipped pest control experts."

Have you spotted any of this furry but dangerous creatures.