Biology and morphometrics of Spodoptera litura (F.) was studied by rearing it on castor under laboratory conditions. Morphology of life stages i.e., egg, larva, pupa and adult along with development period were observed. The width of head capsule was observed at each moult as 0.19, 0.25, 0.45, 0.71, 1.31 and 2.13 mm, respectively. The mean growth ratio of S. litura was observed as 1.64, which indicated that increase in head width in instars was only slightly varying from Dyar’s law.