This study was carried out to survey the main piercing–sucking insect species that infesting maize plants in Zagazig district, Sharkia Governorate, Egypt during 2020 and 2021 seasons, in addition to estimate the effects of potassium fertilization on populations of aphid, leafhopper and planthopper insects. Plant samples, sweeping net, yellow sticky broad traps were used to collect these piercing–sucking insects from different potassium fertilized maize plants. Results showed that aphid species that infesting maize plants were Rhopalosiphum maidis, R. padi, Aphis gossypii, the leafhoppers were Empoasca decipiens, E. decedens, Cicadellina chinai,C. bipunctella zeaand Balclutha hortensis, and the planthoppers were Sogatella vibix and S. furcifera. Potassium fertilization of maize plants influenced the population density of the aforementioned homopterous insect species. The highest mean number of the aforementioned homopterous insect species occurred with F1 (zero potassium fertilization) treatment, while the lowest population density was recorded with F4 (150 kg. Potassium sulphate/feddan). Chemical analysis showed a reverse relationship between protein and carbohydrate contents and aphid, leafhopper and planthopper populations on all tested potassium fertilized maize plants, while a positive relationship between pH values and the aforementioned insect populations was obtained.