The present work was carried out to study the effect of four nitrogen fertilizer levels (40, 60 80 and 100 Kg. N./Feedan) on the infestation by beet fly, Pegomya mixta and sucking insects, Aphis gossypii, Bemisia tabaci and Empoasca lybica as well as sugarbeet yield during two successive seasons (2005/2006 and 2006/2007) in Mallawi, El-Minia Governorate. In both seasons, the highest rates of infestation by P. mixta larvae as well as nymphs and adults of A. gossypii, B. tabaci and E. lybica  were obtained from fertilization with 100 Kg. N./Fed., whereas, the lowest infestation rates were recorded on sugarbeet plants fertilized by 40 Kg. N./Fed. The maximum root and sugar yields were obtained from sugarbeet plants received 80 Kg. N./Fed. The minimum root and sugar yields were produced from fertilization by 40 Kg. N./Fed. Fertilizer application at 80 Kg. N./Fed. could be useful in reducing the yield losses due to these insects and increase the root and sugar yields.