Spintor 24 sc is a new class of insecticides. It is a mixture of two active naturally occurring metabolites spinosyns A and D produced by the actinomycetes Saccharopolysposa spinosa. Spintor has a broad spectrum of activity against many insect pests of vegetables and field crops but spares beneficials. The obtained results of laboratory and field experiments showed that. Spintor 24 Sc at a rate of 0.125 ml/L caused high mortality reached to 84% and 71.5% to 2^nd and 4^th instars of S. littoralis larvae, respectively. It causes also malformation of pupae and moths. 38.5% of pupae obtained from 2^nd instar treated larvae, and 43.8% of emerged moths were malformed. 75 pupae and 57 moths were obtained from rearing of 200 treated 4^th instar larvae. 24% and 15.8% of them were malformed respectively. The hatchability of eggs deposited by emerged moths decreased to be 50.1% compared to 93.8% of control. The eggmasses laid by moths, which exposed during 2^nd larval instar to Spintor, have less number of eggs than those laid by untreated ones. It ranged between 22 and 62 eggs/eggmass with an average of 43.9 eggs/eggmass compared to that of control treatment which has an average of 70.2 eggs/eggmass. Degradation of impact of Spintor on different stages of S. Littoralis has been observed under field conditions. The endmortality of 2^nd instar larvae, which fed on cotton leaves 1 hour after spraying in the field, reached 80%. The mortality decreased with increasing the time elapsed after spraying, till it reached its lowest percent of (33.3%) on the 7^th day after spraying. The effect of Spintor on larvae, pupae, moths and hatchability of deposited eggs proved that Spintor 24 sc may prevent building up of high populations of the cotton leaf worm in the treated fields year after year.