This year, there are more of these pests about than ever before. Their hairs are toxic to both pets and their owners, since they can cause an allergic reaction. Dogs are particularly at risk off the lead, as they can step on the caterpillars, then lick the hairs off their paws. This can cause the tongue to swell and suffocate the dog in the worst case scenario, or they may end up having to have part of their tongue amputated.
The caterpillar nests look like big balls of cotton wool, and you can see the caterpillars moving around inside them. As the name implies, they can mainly be found in pine trees. If you see the nests in your local dog walking area, avoid it until the caterpillars go to ground in late March or early April