The synthesis of six new pyrazoline derivatives was performed by reaction of the corresponding chalcones with semicarbazide hydrochlo­ride and thiosemicarbazide. The insecticidal activity of these compounds in comparison with the bacterial insecticide (bactospeine) and the py­rethroid (fenvalerate) on S.littoralis was studied. The findings indicated that the compound (1) (R^-i, R² = C6 H_5, X = 0,Y = H) showed the high­est toxic effect followed by the thio analogue compound (2) in which X = S. Two days after treatment, their [C50 values were 170 and 480 ppm, which dropped to 130 and 140 ppm, respectively after 7 days. The corresponding figures ranged from 9400 to 600 ppm with bactos­peine and 16-1.2 ppm with fenvalerate after 2 and 7 days, respectively. Furthermore, the synthetic pyrazolines affect the larval development with the highest potency of the derivative (2), showing ED50 of 40 and 12 ppm on pupation and moth emergence, respectively. In case of bac­tospeine, these values were 280 and 140 ppm, while reached to 0.6 and 0.27 ppm with fenvalerate, respectively.