The effect of shifting Spodoptera littoralis larvae from a host plant to another pointed out that pupal weight, growth index, female longevity and fecundity were affected. Host plants considered were okra, tomato and castor oil plants. Larvae were reared for three successive generations under laboratory conditions (25-30˚C, 70%R.H. and 12D:12L) on each of the three chosen plants, and then shifted to each of the other two hosts.             Larvae reared continuously on castor oil leaves, okra and tomato leaves then shifted to either one of the other plants induced a highly significant decrease in the mean pupal weight. Shifting from the favourable host (castor oil leaves) to either okra or tomato leaves, highly significantly decrease the growth rate and the mean number of eggs deposited by the female. Shifting from castor oil leaves to either okra or tomato induced insignificant increase in the female longevity. Phytochemical analysis showed that, castor oil leaves, possess a high value of total carbohydrates, total proteins and nitrogen meanwhile the phenolic compounds were present at a low value level. Biochemical analysis showed that both essential and non essential amino acid were higher in the hemolymph of the last larval instars of S. littoralis reared on castor oil leaves. A noticeable decrement was detected in the amino acid level of larvae fed on okra leaves followed by more decrement in larvae fed on tomato leaves.