The mystery nibblers have interrupted a pool party in Bolingbrook and picnics at Ravinia. They've been blamed for itchy splotches from western Kane County to Michigan vacation grounds. They've attacked in Willow Springs, Chicago Heights and La Grange. Nobody knows exactly what's causing the rash of rashes, but authorities think they've got a good idea of what they're dealing with, anyway—and they warn that it's likely something small, invasive and really annoying. Biting mites. "We don't have positive identification on the type of mite that it is. We do know that it is a mite," said Kitty Loewy, spokeswoman for...