The effects of intercropping aromatic plants (AP) on behavior and population development of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) were investigated in the field (adults) and in the greenhouse (nymphs). The responses of adults to the volatiles of tomato, Solanum lycopersicum L. (Solanaceae), plants plus AP [T + coriander (Co), rue (R), marigold (M), Greek basil (B), or citronella (Ci)] vs. humidified air or tomato volatiles only were assessed in laboratory Y-tube olfactometer assays. We found higher responses of adult B. tabaci to the humidified air than to the T + Co, T + B, and T + Ci treatments. The responses to T + R and T + M were similar to those to the humidified air. Responses to tomato volatiles were also greater than to T + Co, T + B, and T + Ci. In field assays, populations of adult insects were evaluated in tomato alone, in tomato intercropped with coriander or Greek basil, and in tomato mulched with citronella grass for 6 weeks. Adult whiteflies were generally found in greater numbers in the tomato-alone treatment compared to tomato intercropped with coriander or basil and tomato with citronella grass mulch. Reduction in adult whitefly populations compared to the population found in tomato alone was 84, 79, and 69% in intercrops of T + Co and T + B, and the tomato with citronella mulch treatment, respectively. Infestations of B. tabaci nymphs in plots of tomato plants cultivated alone or intercropped with reseeded coriander plants were also determined in a greenhouse. Nymph counts in the greenhouse assay were generally lower in tomato intercropped with coriander than in tomato alone for all six assessments. The mean reduction in nymphs in tomato intercropped with coriander was 37.7% compared with tomato alone. These results indicate that intercropping aromatic plants reduces infestations of B. tabaci.