Abstract: 【Aim】 The external morphology including the gnathosoma, idiosoma, external genitalia and legs of Dermatophagoides pteronyssinus was observed by using scanning electron microscopy (SEM). 【Methods】 D. pteronyssinus mites were collected from the dust of beds and pillows, and the living adult mites were isolated using the stereoscope and observed with SEM. 【Results】 SEM photographs showed that the cheliceraeare clamp-like and palps flat. Cuticle is covered with fine striations like fingerprint, with distance between striations less than 2 μm. Oviporus of female genitalia is located at the center of the ventral surface of the idiosoma. The male genitalia has a pair of leaflike genital folds. Anus is a longitudinal hole, with two anal suckers in the male. The end of each tarsus of female has a pulvillus, and the tarsus of leg Ⅳ of the male has two suckers. 【Conclusion】 The observations on D. pteronyssinus provide more evidence for identification of dust mites.

Key words: Dust mite; Dermatophagoides pteronyssinus, adult mite, morphology, scanning electron microscopy (SEM)