The present work was conducted during the two successive seasons of 2015/2016 and 2016/2017 in order to study the seasonal abundance of aphids, leafhoppers and planthopper insects infesting maize and sugar beet plants in Diarb-Nigm District, Sharkia Governorate, Egypt. On maize plants the following aphid species occurred: Rhopalosiphum padi (Linnaeus), R. maidis (Fitch). and Aphis gossypii (Glover).While, the leafhopper and planthopper insects included Empoasca decipiens (Paoli), E. decedens (Paoli), Cicadulina chinai (Ghauri), Segatella vibix (Haupt) and S. furcifera (Horv). On the other hand, sugar beet plants were infested with one species of aphid i.e. Myzus persicae (Sulzer) and three species of Leafhoppers i.e. Circulifera tenellus (Baker), E. decipiens (Paoli), and E. decedens (Paoli). The aforementioned insect pests were collected by three different methods from maize and sugar beet plants using plant sample, sweeping net and yellow sticky board trap. This research aims to utilize the obtained results in developing the integrated pest management (IPM) programs against the aforesaid insect pests through the effect of atmospheric temperature and relative humidity on the population of these insects.