Rat mites are tiny parasites that live on rats and inside their nests and feed off rat blood. But sometimes, when they can't find rats to infest, they resort to making a meal out of the blood of humans. They are capable of surviving for long periods without a host and they can travel several hundred feet from a rat or a rat's nest to find a new host. When they bite your skin they cause a dermatitis similar to bedbugs. You may notice raised, red, itchy bumps on a specific section of your skin. A similar problem exists with bird mites. Of course, the long-term solution is to eliminate rodent and bird nests. There are thousands of species of mites and some cause allergic reactions. If you need professional help give us a call.