The purpose of this study was to investigate the effects of calcium carbonate and saccharides on the feeding behavior of newly hatched larvae of the silkworm, Bombyx mori L. Japanese strains, "Hi", "KAI", "Ryo" and "Yo", and Chinese strains, "Kai", "Bono", "Kenpaku" and "Tsukuba", were used for the experiments. Calcium carbonate (CaCO 3) and sucrose were added to the basal diet, consisting of cellulose powder, agar and distilled water. This was fed to the larvae immediately after they hatched. It was found that the feeding of any variety of silkworm was improved by the synergetic effects of CaCO 3 and sucrose. The amount of feeding for "Kai" and "Bono", however, were notably less than those of the other varieties. Next, diets containing CaCO 3 and two kinds of saccharides were fed to both the "Kai" and "Bono". The amount of diet consumed by "Kai" and "Bono" remarkably increased when CaCO 3 was used together with sucrose and myo-inositol, and CaCO 3 together with glucose and myo-inositol, respectively. The above results indicated that CaCO 3 combined with sucrose or other saccharides synergistically stimulated larval appetite. Also it was found that CaCO 3 could restrict larval movement to the area immediately surrounding the diet.