The effect of supplementation with potassium nitrate on biochemical constituents was analyzed following treatment of last larval stadium. The fat body glycogen and haemolymph trehalosre significantly increased in all the treated groups. The fat body and haemolymph protein also increased significantly in all the treated groups except 500 ${mu}g$/ml where increased fat body protein and decreased haemolymph protein were not significant. The total lipids, phospholipids and neutral lipids of the fat body increased significantly in all the groups except 50 and 300 ${mu}g$/ml where the fat body phospholipids increased but the increase was not significant. However the total lipids, phospholipids and neutral lipids are significantly decreased in 500 ${mu}g$/ml treated group when compared with that of the carrier control.