Abstract: Whiteflies have attracted intensive attention from many agriculturists due to their direct feeding and plant virus transmission. The economic losses depend on certain species population existing on the field during chilli-pepper cultivation. More over, biotype characteristic will determine the effectivity of applied pest management. Based on this, detailed information on whiteflies in chilli-pepper cultivation is very important. We applied mitochondria cytochrome oxidase unit I gene sequence for detecting species and biotype of whiteflies existing in West Sumatera. Two species were successfully identified i.e., Bemisia tabaci and Trialeourides vaporariorum that are dominant in this region. Distribution of both species are separated by altitude, where B. tabaci exist predominantly from low altitude to medium altitude, whereas in high altitude it is not common. On the other hand, T. vaporariorum distribute mainly in high altitude and not in medium altitude. Furthermore biotype determination on B. tabaci identified the existence of B biotype in all areas studied.