An army of killer caterpillars could invade Hounslow, health experts have warned.

Oak processionary moths are covered with tiny barbed hairs which cause an allergic reaction that can prove lethal in the most extreme cases.

The pests, which are mainly found on oak trees, are native to southern and central Europe but nests were discovered in trees across west London last summer, including Syon Park and Kew Gardens.

And as the bugs prepare to change into moths, the time they are at their most deadly, experts have warned they may be on the loose in Hounslow.

Topher Martin, head gardener at Syon Park, said keepers had found three nests last year, all of which were immediately burned but added that the caterpillars posed no greater threat than bees or wasps and visitors would only be warned if there was a significant problem. A spokeswoman for Osterley Park said it was aware of the threat but no nests had been discovered.

Residents have been warned to look out for the caterpillars, which are grey with a dark stripe along their backs and are covered with long white hairs.

Anyone finding the caterpillars or a nest should call Hounslow Council on 020 8583 5555 or email: