Because the harvesting season for mulberry leaves occurs only twice a year, to prepare a fresh and large quantity of silkworm powder, we developed two types of artificial feed, named K40 and K95, which contained 40% and 95% of mulberry leaf powder, respectively. We investigated the apparent viscosity of the mulberry-bred, K40-bred and K95-bred silkworm blood of the beginning and final stage of the fifth period. The viscosity of those bloods at the beginning stage was lower than that at the final stage, suggesting that the physiological circulatory conditions of silkworms at the beginning stage are better than those at the final stage. Also, the results revealed that the order of the viscosity was K40-bred silkworm blood> K95-bred silkworm blood> mulberry-bred silkworm blood, irrespective of the growth stage. Moreover, the trehalose content of silkworm blood was inversely correlated to the viscosity (R=-0.84), showing an inverse relationship between the nutrient contents and the viscosity. Thus, we developed a good silkworm powder using the artificial feed K95, from both a rheological and nutritional point of view. Furthermore, we found that silkworms markedly concentrate 1-deoxynojirimymycin, a potent glycosidase inhibitor, in their body system, suggesting that silkworm powder is more effective for the suppression of the blood glucose level than mulberry leaves themselves.