The two most hazardous vectors for humans are Culex pipiens molethus and Musca domestica.Several environmental and health issues have emerged because of the overuse of chemicalpesticides. This study sought to determine the efficacy of aqueous, alcohol, and oil extracts ofCitrullus colocynthis L. plant under in vitro conditions using different concentrations (0, 5, 10, and20 mg/mL) on the various stages of Culex pipiens molethus and Musca domestica. It also sought toidentify natural biological alternatives to synthetic insecticides. The current research revealed thatthe adult and juvenile stages of mosquitoes and house flies were considerably impacted by theextracts of bitter melon. Concentrations demonstrated a distinct effect and significantlyoutperformed the control treatment after 24, 48, and 72 hrs of exposure. Compared to other bittermelon extracts, the impact of the oil extract of C. colocynthis was superior. At a dosage of 20mg/ml, oil extract treatment significantly reduced hatchability and increased mortality in thesecond and fourth larval stages of C. pipiens molethus. The outcomes also demonstrated thesuperiority of the oil extract of C. colocynthis in influencing the different stages of the house fly M.domestica with the same previous concentrations (20, 10,5 mg/mL) on egg productivity (22, 72,89, 82%) and third larval instar (66, 79, 71, 94, 82.88%) mortality rates, as well as pupae weightrates (0.10, 0.11, 0.100 mg). With the help of the current study's findings, we may suggest usingbitter melon extracts, particularly the oil extract, as a potentially effective control measure againstmosquitoes and house flies. These naturally occurring extracts, which do not contain any industrialchemicals, are difficult for the insect they are intended to kill to withstand. For the aim ofunderstanding the mechanism of action of these extracts on mosquitoes and house flies, as well asunderstanding the effect of bitter melon extracts on numerous therapeutic insects in the future,more research is necessary.