尘螨（学名：Dermatophagoides pteronyssinus）是一种8只脚的微小的蛛形纲节肢动物，长170－500微米，宽250－322微米，雌雄个体均为乳白色，肉眼是几乎看不到的，最喜欢生长在温暖潮湿的环境中，适合生长的温度为22－26℃、湿度为70－80％，以人类或动物（猫、狗）脱落的皮屑、毛发维生，以位于亚热带的**为例，室内温度平均约15-30℃，相对湿度约60－85%，利于尘螨生长，亦是**儿童重要的过敏原之一。**市卫生局于2008年发布的统计数据中，对国小一年级学童过敏原检测，尘螨占90.79%。

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.