Acari are part of the arachnid family and are better known as mites and ticks. While many believe that mites and ticks only feed on blood, some of the sub-species feed on plants, decomposing organic matter, and even soil. Most have the same body features: two body regions and six or eight legs, depending on life cycle. Acari can be anywhere from microscopic to half an inch long and have many different names based on size. Almost every sub-species carries disease-causing organisms including Lyme disease, Colorado Tick Fever, Q-fever, and relapsing fever. Mites and ticks are also known to stimulate asthma in humans.