Toxic caterpillars that can cause asthma, vomiting and other allergic reactions, have been spotted in Merton.

The Oak Processionary Moth was found in Mostyn Gardens, South Merton, earlier this week.

While the moths themselves are not thought to be harmful, the hairs on its caterpillars can cause serious allergic reactions.

Cases of skin rashes, sore throats, breathing difficulties and problems with sight have been reported in humans and animals after contact with the caterpillars in previous cases.

The Forestry Commission says these oak processionary moth 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 nests on trunks and branches.

Even if the caterpillars are dead, you should not touch them as they are still highly toxic.

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.

What should I do if I see some?

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