It has been indicated that muga silk industry has the feasibility and economic viability in Assam. Probably due to its restricted habitat in the North-Eastern Region, the muga silk insect has not drawn much attention of the people from other parts of the world and almost very negligible research work has been done on the same. Recently Cooch Behar district of West Bengal has come to the fore. The environmental conditions throughout the year are not suitable here. No systematic research work has been initiated to correlate the environmental parameters with rearing performance and formulation of a year-round schedule is necessary for successful muga culture in Cooch Behar. The present investigation has been undertaken to assess the environmental impact on rearing and grainage performance of muga silkworm in order to determine the optimum environmental conditions for best rearing in Cooch Behar district of West Bengal, a newly explored area of muga culture under terai region.