Mites are small arachnids that belong to the tick and spider family. They are not insects and are more closely related to ticks and spiders. Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. Most mites are tiny, less than 1 mm (0.04 in) in length, and have a simple, unsegmented body plan. Mites have two regions in their body plan, a cephalothorax (with no separate head) or prosoma, and an opisthosoma or abdomen. Mites have different eating, biting, and bloodsucking habits, and there are thousands of different species of mites. Some mites do bite animals and humans, and examples of mites that bite humans include chiggers and dust mites. Mite bites can cause skin rashes on the legs, arms, and trunk, and general signs to look for include small, hard bumps on the skin, red patches of skin, irritation, itching, or swelling near the bites. Dust mites live in house dust, mattresses, furniture, and carpets, and they feed on dead skin and dander that falls off of humans and pets. These tiny creatures do not bite or live on humans, but proteins in the exoskeletons and feces of dust mites can induce allergic reactions in people.