Infestations of the sweetpotato whitefly,Bemisia tabaci(Gennadius), in fields of spring-grown cantaloupes,Cucumis meloL., near Yuma, AZ, were measured by counts of eggs, first to mid-fourth instars, late-fourth instars (red-eyed nymphs) and adults. All stages were sampled from leaves at the terminal and crown portions of the plant. Adults were sampled at 0700 and 1300 hours on the entire leaf, and immature stages were counted in a 1-cm2area from each of four quadrants of a leaf. Adult whiteflies were more abundant on samples collected at 0700 hours and on terminal leaves in all fields. There were no significant differences between leaf sections for any immature life stage, but red-eyed nymphs were more abundant on crown leaves, whereas eggs had higher densities on terminal leaves. The power law and patchiness regressions indicated that all life stages were aggregated, but there were distinct degrees of aggregation between leaf positions.