author(s)
Shilpi Devi Borah, Monimala Saikia and Praban Boro

abstract
This research work was carried out to find out the larval parameters of two commercial eco-races i.e borduar and kokrajhar of eri silkworm (Samia ricini Donovan) by feeding them with two different food plants viz., castor and borpat separately and along with this we also find out which one eco-races, food plants and seasons were better than another one by maintain four replication in each treatment during spring and autumn season. It was observed that castor is the best food plant for rearing of eri silkworm during the both seasons. Larval parameters such as full grown larval weight, mature larval weight, effective rate of rearing (ERR) were recorded higher in borduar eco-race in spring season except the larval duration which was observed to be shorter on kokrajhar eco-race during autumn season when fed with castor leaves.