The present investigation  aimed to study the effect of the chemical fertilizer[ N P K ] on traits of larval weight , fresh cocoon weight , cocoon shell  weight , pupae weight  , silk ratio,5^th larval duration ,number of egg / female , egg fertility and hatchability. This investigation was carried out at Department of Plant Protection, Faculty of Agriculture, Mansoura University. The treatments with chemical fertilizer at recommended dose resulted significant increase for alltraits comparing control. Also results showed that reared during spring was better than autumn. Interaction between chemical fertilizer and season reported is better.