Samples of whiteflies were collected from Dendranthema spp. in major growing areas of Tanzania. The insects were transferred onto test plants to confirm host specificity. Infested with insects, test plants were then protected with polyethylene bags. Samples of whiteflies from infested plants were taken at 10 day intervals post-infestation (dpi), 28 dpi and 35 dpi, for behavioural studies. At 10 dpi eggs were seen as oval bodies while at 28 dpi crawling bodies and newly emerged adults were observed, leaving behind characteristic shiny hollow cases. At 35 dpi, all the stages of development were seen. The features observed are typical of Bemisia argentifolii and the area is endangered by the occurrence and spread of viruses transmitted by this species. This identification, which is an integral part of pest surveillance, initiates a study of the viruses and will lead to pest records for regulatory purposes. The international scientific and trading community is assured that the report reflects the real situation. The pest is thought to be present in the reported areas only and the pest status is actionable and under surveillance.