Oviposition and feeding response comparisons for the silverleaf whitefly (Bemisia argentifolii Perring) and sweetpotato whitefly (Bemisia tabaci (Gennadius)) were studied under field conditions on four host plants at the University of California, Riverside. Preference-performance relationships were studied for each species under no-choice conditions using small cages on cotton, cucumber, zucchini squash, and tomato. Additionally, the feeding and oviposition preferences of an endemic population of silverleaf whitefly were measured for the same hosts under a multi-choice situation. Both whitefly species preferred cotton for adult feeding and cucumber and zucchini for oviposition and immature feeding. Developmental and population growth rates for B. argentifolii exceeded those of Bemisia tabaci on all hosts. Additionally, adults of both species preferred older leaves, while immatures predominated on younger leaves.