For several years, whiteflies of the genus Bemisia (Hom., Aleyrodidae) have caused major damage to vegetable crops in the Lesser Antilles, and have revealed new symptoms. The genetic characterization of the populations involved was attempted using esterases polyacrylamide gel electrophoresis. Most of the individuals analysed showed an identical enzymatic profile, which also appears to be similar to the profile of Bemisia argentifolii (Bellows and Perring) described in the United-States. However, the individuals collected on Jatropha gossypifolia (L.) were different, and matched the N biotype of Bemisia tabaci (Gennadius) known in Puerto Rico.