Whiteflies cause major agricultural problems in environments ranging from arid to humid climates on a global scale. A study was conducted on the effects of vapor pressure deficit (VPD) on oviposition, hatching, body size, and survival of immature B-biotype sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). Experiments were conducted at VPD conditions of 0.5, 1.7, and 2.7 kPa to represent low, medium, and high VPD environments, respectively. The study was conducted at 26°C with insects reared on collard, Brassica oleracea ssp. acephala de Condolle. The rate of oviposition was decreased at the highest VPD treatment. However, percentage egg hatch was not significantly affected by the treatments. More time was required for eggs to hatch at a high (2.7 kPa) compared with a low (0.3 kPa) VPD in a separate experiment. Overall survival to the adult stage was decreased at the highest VPD (≈50%) compared with the other two VPD environments (≈75%). Sizes of males and females were different, as is well known, but VPD had little significant effect on adult body size (length and width). The size effect was erased when the F₂ generations from the different treatments were reared under a common environment. Insect population models that include the most relevant environmental parameters can offer the best estimation of life-history events. These results help elucidate the ecology of B. tabaci and indicate that extremes in ambient moisture can have an impact on populations.