Insect growth regulators activity against the Lepidoterous pest Euproctis icilia and Euproctis fraterna was observed. The effect of Penfluron and Diamino-furyl-s-triazine. Two type of treatment given larval feeding treatment. A activity on weight loss of the both experimental insects larvae included third instar as well as fifth instar. The administration of penfluron and diamino-furyl-s-triazine was done by feeding technique to Euproctis icilia and Euproctis fraterna larvae, to see its interaction on the experimental insect. The effect of the chemical at lethal and sublethal levels was recorded. The parameter of study was growth and weight loss during exposure period.