In summer 2007, an outbreak of what were called “itch mites” broke out in Chicago. As of September, scientists were trying to determine which species of Pyemotes mites caused the outbreak. Pyemotes mites are traditionally associated with galls on oak trees. Interestingly, the article suggests that was not the case here:
Because it has been difficult to find oak leaves with midge galls, and reports of bites and rashes were coming from neighborhoods that had few, if any, oak trees, the mites may have built their population on a food source other than oak gall midges.
There are links to more information on Pyemotes mites in our useful resources page.