The within‐plant and between‐plant distribution of the cotton whiteflyBemisia tabaciwas studied in cotton fields (cv. Deltapine 15/21) near Adana/Turkey and two methods of estimating nymphal numbers on single leaves were tested in order to develop an optimal sampling technique. Counting the nymphs on only one leaf sector as well as rating the leaves according to a logarithmic scale can largely reduce the counting effort. The latter method results very often in overestimation, but this drawback can possibly be overcome by better training of the observers. The main stem nodes 3–7 (counted from the top) constitute, in general, the region most infested by third and fourth instar nymphs during the early growing season; leaf samples taken from this region give the best results.