The effectiveness of three insecticides, imidacloprid, lambda-cyhalothrin, and cyantraniliprole, in their conventional and nanoemulsion formulations, were evaluated under laboratory and greenhouse conditions using the recommended dose against the cotton aphids, Aphis gossypii Glover (Hemiptera: Aphididae). The prepared insecticide nanoemulsions exhibited polydispersity indices ranging from 0.198 to 0.324 and zeta potentials between -27.2 and −38.1 mV. The most minor insecticide nanoemulsion droplet diameter was lambda-cyhalothrin (83.25 nm), and the largest was imidacloprid (112.32 nm). Preparing the imidacloprid, lambda-cyhalothrin, and cyantraniliprole as nanoemulsion formulations increased the toxicity by by1.41, 1.78, and 1.25-fold after 24 hr., and 1.46, 1.7 and 1.45-fold after 48 hr., respectively against A. gossypii under the laboratory condition. Lambda-cyhalothrin showed the highest toxicity against A. gossypii, with fifty lethal concentration (LC50) values of 5.313 ppm and 1.808 ppm after 24 hrs. and 48 hr., respectively. Under the greenhouse conditions, the general means of reduction percentages of A. gossypii populations caused by conventional formulation of lambda-cyhalothrin, imidacloprid, and cyantraniliprole were 88.2, 81.74 and 78.91 %, respectively. While these means for the nanoemulsion formulations were 95.17, 86.2 and 85.91 %, respectively. After the second spray, these means recorded 87.72, 82.78, and 82.18 % for conventional formulations and 91.22, 88.23, and 87.31 % for nanoemulsion formulations, respectively.