Spray droplet deposition on C. chinense leaves was observed to vary according to the vertical position of the leaf on the plant canopy. The mean number of droplets was highest and lowest on leaves located in the upper and lower third of the plant canopy, respectively. B. tabaci mortality due to Aza-Direct^®-treated leaves was not significantly influenced by cardinal direction. However, the location of the sprayed leaf (upper, middle or lower third of canopy) along the vertical axis had a strong influence on B. tabaci mortality. Mean B. tabaci mortality on sprayed leaves in the middle third of the canopy was 6.20% higher and significantly different from that on leaves in the lower third. The age of the Aza-Direct^® residue also had an influence on the mortality of B. tabaci adults, with highest and lowest mortality being recorded on leaves located in the upper and lower third of the plant canopy, respectively. Adult B. tabaci mortality generally decreased with increasing Aza-Direct^® residue age. Degradation of Aza-Direct^® residues was most rapid on the upper leaves and was 1.4 times faster than that on the leaves on the lower third of the plant canopy while it was 1.1 times as fast on the middle leaves.