Solvent extraction, a classic method to separate different components, was used in this study. Clove (Syzygium aromaticum) was macerated using four solvents, namely, water, petroleum ether, ethyl acetate, and ethanol, to extract the essential oil. The insecticidal and repellent activities on third-instar larvae and adult females of Culex pipiens were investigated. Based on LC₅₀, water extract was more active (LC₅₀ = 39 ppm) against larvae. The highest efficacy of the repellent solvent of the clove extract against adult females was 28%. The ultrastructural effect was studied on the cuticle, muscles, and midgut of third-instar larvae. The tested larvicide showed histopathological changes in the treated larvae compared with the untreated ones. Thus, the water extract could be a good candidate and promising alternative in control programs of mosquitoes, especially against Cx. pipiens in Egypt and other developing countries.