The caterpillars, which are covered in thousands of toxic bristles , were spotted in Kew Gardens recently. Luckily, the garden's staff are on top of the situation and won't let the caterpillars turn into an infestation of Oak Processionary Moths. The incredibly high-tech solution to getting rid of the caterpillars is spraying them with hairspray and setting them on fire. At least their toxic bristles will be properly styled before they meet their sad demise.
The adult moths emerge in late July, so now's the time to get rid of them. If you're in West London and spot a bunch of the caterpillars, it's probably a good idea to give the authorities a call to remove them. Your local council will either be able to deal with them, or point you in the right direction.
Image taken from eek the cat's Flickr photo stream