The
house dust mite (
HDM) is a
cosmopolitan pyroglyphid that lives in
human habitation. Dust
mites feed on organic detritus, such as flakes of shed human skin, and flourish in the stable environment of dwellings. House dust mites are a common cause of
asthma and allergic symptoms worldwide. The mite's gut contains potent digestive enzymes (notably
proteases) that persist in their feces and are major inducers of allergic reactions such as
wheezing. The mite's exoskeleton can also contribute to allergic reactions. The
European house dust mite (
Dermatophagoides pteronyssinus) and the
American house dust mite (
Dermatophagoides farinae) are two different species, but are not necessarily confined to Europe or North America; a third species
Euroglyphus maynei also occurs widely. Unlike
scabies mites or skin follicle mites, house dust mites do not burrow under the skin and are not parasitic.