These microscopic spiders make their homes in housedust, as their name implies. They are harmless, not biting nor causing illness – except for people with allergies. We speak of being allergic to dust mites but really it is dust mite droppings and decomposing bits which are the actual causes of allergies. Contrary to rumors widely circulated on the internet, dust mite debris does not double the weight of your mattress and feather pillows fight dust mites better, not worse, than polyester.
Dust mites do not drink, but absorb water directly from the air. Therefore lower humidity helps keep mite populations down. If pollen counts are not too high, airing bedding or throw rugs in direct sunlight for a couple of hours on a hot, dry day will kill the mites (but, don't forget, allergies are caused by mite droppings, not mites, so wash or vacuum thoroughly after sun treatment).