It’s been a late, wet spring on Exmoor, but among the warm, damp oak-leaf litter of Hawkcombe Wood, caterpillars are moving slowly, chewing languorously on shoots of cow-wheat (Melampyrum pratense), preparing to pupate.
These are the larvae of one of the UK’s rarest butterfly species, the heath fritillary (Melitaea athalia). Their black and white bodies are studded lengthwise with tan bobbles, each cone sprouting a cluster of short bristles. Next month, the adults will emerge, flitting and gliding close to the ground on white-edged wings patterned with amber and brown.
