The phytochemical screening of active constituents were studied in the aerial parts of Euphorbia retusa and Calotropis procera wild plants.             Data indicated the occurrence of sterols and triterpens, phenolic glycosides, anthraquinon glycocides, saponin, flavonoides, cardiac glycosides, alkaloids and carbohydrates and /or glycosides,with variable degrees of occurrence due to the plant species. The two plant materials were extracted with chloroform and methanol, then evaluate their potency against 2^nd instar larve of cotton leafworm S.littoralis as well as the conventional insecticide chlorpyrifos either alone or in combination with each other.             Data revealed that LC₅₀ values were [ (0.32 and 1.55) , (2.92 and 5.59) and 7 × 10^-5 % ] for methanolic and chloroformic crude extractes of the two tested plants and chlorpyrifos respectively. The co-toxicity values of chlorpyrifos + Euphorbia retusa methanolic extract at 1:1 , 2 : 1 and 1:2 mixing ratio were [(-50, + 60.17 and – 25.93 ) and (- 49.24 , - 84.92 and – 70.46 )] respectively. While in case of chlorophormic crude plant extracts in the same manner were [(+2.31, - 43.33 and 76.47 ) and (-34.84 , - 50 and – 37.04)] respectively.