The silverleaf whitefly, Bemisia n. sp. is a major pest in cotton Gossypium spp., cucurbits Cucurbita spp., tomatoes Lycopersicon esculentum L., cole crops Brassica spp., and many ornamentals. Its entry into the U.S. is recent; its origin is unknown. Identification of the silverleaf whitefly as a new species explains why a closely related pest, the sweetpotato whitefly Bemisia tabaci (Gennadius), was reported to exhibit previously unknown biological characteristics and behaviors, and to cause severe economic damage to several crops, including new host crops. The silverleaf whitefly is characterized by an exceptionally wide host range, A high rate of reproduction, and a large capacity to detoxify both natural and synthetic xenobiotics. It is a vector for a previously undescribed virus, tomato mottle gemini virus. In addition, factors associated with its feeding induce plant disorders such as squash silverleaf and irregular ripening of tomatoes.