Sightings of a hairy caterpillar, that can make humans and pets very unwell must be reported this summer – but people are being urged not to touch them. England is about to enter its ‘greatest risk period’ when oak processionary moth caterpillars emerge before turning into adult moths. Their appearance – usually between mid May and July – can pose a risk to the public and their animals because the creatures and their nests contain long hairs that can cause itchy rashes, eye and throat problems and sometimes breathing difficulties. The caterpillars – say officials and wildlife charities – shoul…