Dust mite allergy is an allergic reaction to tiny bugs that commonly live in house dust. Dust mites are microscopic bugs in the spider family. They can survive in all climates and at most altitudes. However, they thrive in house dust in warm environments, preferring the "70s"—70 degrees Fahrenheit (21 C) and 70 percent relative humidity. Dust mites, close relatives of ticks and spiders, are too small to see without a microscope. Dust mites eat skin cells shed by people, and they thrive in warm, humid environments. In most homes, bedding, upholstered furniture and carpeting provide an ideal environment for dust mites.
Dust mites feed on the dead skin cells people regularly shed. If that weren't creepy enough, dust mites also don't need to drink water—they simply absorb it from the moisture in the air. Dust mites not only prefer to live in dust, they also add to it by leaving behind tiny mounds of feces and decaying corpses. It's the proteins in this detritus that may be the only reason most people even know about these mini-monsters—that's because it causes a whole lot of allergies.