^BMite-infested trachea.^b Light micrograph of normal (left) and infected (right) tracheae (airways) from a honeybee (^IApis mellifera^i). The trachea at right is infested with honeybee tracheal mites (^IAcarapis woodi^i). Mites are related to spiders, and many are parasites of other animals. These mites cause a condition known as acariosis or acarine disease. It makes the bees lethargic and unable to fly, and can cause entire honeybee colonies to collapse. Pairs of tracheae are located in the thorax and abdomen of honeybees. They form the respiratory system by which gases diffuse into and out of the honeybee's tissues.