Armyworm (Spodoptera frugiperda) is an important pest of corn crops in Indonesia that attacks in the vegetative phase to the generative phase. Light is one of the factors that can affect the growth and development of S. frugiperda which is divided into two phases, namely photophase (light period) and photophase (dark period). This study aims to observe and analyze the effect of light on the length of larval instar, pupa and imago, body length, body weight, paternity, fecundity, fertility, and sex ratio of S. frugiperda. Test insects S. frugiperda were obtained from BSIP-TAS in the 1st instar larval phase. The results showed that the light period (24L:0D) showed that constant light could extend the larval, pupal, and imago instar length, body length and reduce the virginity, fecundity, and fertility of S. frugiperda. The 24L:0D treatment also showed the heaviest body weight compared to the other treatments.