Coloured scanning electron micrograph (SEM) of Dust mite (Dermatophagoides pteronyssinus). Millions of dust mites inhabit the home, feeding on dead human skin that are common in house dust. The mite's body is in three parts: the gnathosoma (head region) adapted for feeding on dead skin, the propodosma (carrying the 1st and 2nd pair of walking legs) and the hysterosoma (locating the 3rd and 4th pairs of legs). Dust mites produce 10-20 waste particles per day. The dead bodies and faecal pellets can trigger allergic responses. The whole life cycle from egg to adult takes approximately one month to complete, mature female mites can lay from 1-2 eggs per day. Adult mites can live up to two months. The most important house dust mites worldwide are Dermatophagoides farinae and Dermatophagoides pteronyssinus. Magnification: x78 when shortest axis printed at 25 millimetres.