Abstracts: Among the many tropical fruits, mango (Mangifera indica L.) has been identified as the most important from socio-cultural, commercial and environmental aspects. It is grown in more than 100 countries. Aulacuspis tubercularis Newsteed (Homoptera: Diaspididae) commonly known as white mango scale, is a serious insect pest of mango in many mango growing countries including Ethiopia. Aulacuspis tubercularis was detected in Ethiopia a decade ago. With no effective control method, the pest spread the whole country, resulting in 50-100% crop losses. The current study was conducted to establish the efficacy of aqueous neem, Azadirachta indica L. (A. Juss) leaf powder in the management of A. tubercularis under field condition. Field experiments were conducted at Arjo Gudetu and Uke experimental sites of East Wollega zone. The treatments were different spray concentrations prepared from aqueous A. indica leaf powder. These were 0.05, 0.1 and 0.15mg/ml of water. Treatments started after complete infestation was observed and continued for three times at 10 day-intervals. The experiment was laid out in a randomized complete block design in four replications. Mortality count was recorded each treatment applications. The results showed that aqueous A. indica leaf powder at 0.15 mg/ml significantly (p<0.05) reduced the population of A. tubercularis at both experimental sites. Male adults and nymphs were more affected than the females. The use of aqueous A. indica leaf powder led to significant population reduction of A. tubercularis and its impact. Hence, the product can be recommended for the management of A. tubercularis.