The polyphagous, ubiquitous, destructive pest, Spodoptera litura(F.) affects 150 host plant species and notably their larval forms arenotorious. Extensive feeding and rapid reproduction cycles led the farmers andindustrialists to seek the effective chemical and synthetic pesticides. Randomand inappropriate usages of pesticides imposed a negative impact on non-targetorganisms, environment and abiotic factors and also pest resurgence to theparticular pesticides. To overcome this unnatural incidence, biopesticides arepracticed as an alternative source. Plant botanicals play a huge role as insectgrowth regulators (IGRs) by inhibiting the regular moulting cycle, developmentand survival of insect pests. Also, the silverback fern, Pityrogramma calomelanosare reported with several secondary metabolites which are known for theirpesticidal properties. Hence, the present work was framed to study the dietaryresponses as well as nutritional indices of S. litura treated with crudeextract of P. calomelanos. The treated larvae showed dietary andpost ingestion responses prior to moulting and death. On the 4th day oftreatment, reduction in food intake (522.89 mg), larval weight gain (41.02 mg),ECI (56.25 %), ECD (46.30 %), AD (47.21 %) and RGR (3.06 mg/mg/day) wasobserved as dose dependent manner except the feacal production (378.18 mg) ascompared to control. Therefore, the ethanolic extract of a fern, P. calomelanoscan be recommended as a biopesticides for its post ingestion andanti-nutritional effects on S. litura larvae.