We investigated the effects of morphological characteristics of cucumber, Cucumis sativus L., seedlings grown at different vapor pressure deficits (VPDs) on initial colonization of whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype B. The seedlings were grown at a VPD of 3.8 or 0.4 kPa for 9 d at 30°C under a photoperiod of 12:12 (L:D) h. Pairs of seedlings, one grown at high VPD and the other at low VPD, were then installed in cages with a VPD of 1.3 kPa, and adults of B. tabaci between 150 and 200 were released. Leaves of high-VPD seedlings had fewer B. tabaci than those of low-VPD seedlings 24 h after release. They also had higher relative chlorophyll content, were thicker and tougher, and had abaxial trichomes with higher density. Water stress caused by the high VPD probably decreased the initial colonization of B. tabaci through changes in these leaf morphological characteristics.