The performance of conventional ground motor sprayer, Motor­ized knapsack sprayer "Solo", and lever-operated sprayer "Solo" were compared for controlling adults and nymphs of the whitefly Bemisia tab-ad (Gennadius). A mixture of Lambdacyhalothrin at 187.5 ml + Diafen­thiuron (500 SC) 60 ml/fed. was applied in cotton fields at Gharbia Gov­ernorate during the growing season of 1995. The conventional ground motor sprayer showed high initial efficacy against the whitefly adults while achieved moderate effect against nymphs. Motorized knapsack sprayer and lever operated sprayer proved less initial effect against the adult stage and no effect on nymphs. The three tested machines showed nearly the same average of bio-residual efficiency against both adults and nymphs.