This experiment was carried out at El-Riad region, Kafr El-Sheikh Governorate to estimate the efficiency of silica nanoparticles compare with bio-insecticides, mineral oil and the conventional insecticide (Dursban H) on reducing the population of the cotton bollworms; pink bollworm, Pectinophora gossypiella (Saunders) and spiny bollworm, Earias insulana (Boisd.) in cotton fields during 2013 and 2014 seasons. Data showed that Dursban H in two sprays was the highest effective. Silica nanoparticles came in the second order with high concentration (200 ppm) followed by low concentration of silica nanoparticles (100 ppm) during the two successive cotton seasons. However, Biovar (Beauveria bassiana) was the least effective. The efficiencies of the tested compounds were significantly differences according to the population reduction of the two cotton bollworms.