Different ages of the two spotted spider mite Tetranychus urticae Koch and the predacious mite Amblyseius gossipi El-Badry eggs were exposed to selected concentrations of cypermethrin (500 ppm), flucythrinate (200 ppm), cyfluthrin (100 ppm), fenvalerate (200 ppm), Pyridaphenthion (25 ppm), dicofol (250 ppm), avermectin (10 ppm), and dimilin (50 ppm). Generally, the synthetic pyrethroids were effective on eggs especially those of A. gossipi. Dicofol was rather toxic to T. urticae eggs, while avermectin was only effective on older eggs of both species. Eggs treated with different pesticides at late stages took longer to hatch, particularly in the case of A. gossipi.