In order to investigate the effects of adding ascorbic acid to silkworm (Bombyx mori) diet, an experiment was conducted involving ascorbic acid treatments. Dietary supplements of 1, 2 and 3% ascorbic acid were fed to 4th and 5th instar silkworm larvae. The larvae were fed by mulberry leaves from Shien Ichenoise variety up to the fourth instar. Then from the beginning of the fourth instar larvae the enriched leaves were fed once a day. The enrichment of the leaves was done by being sprayed by the treatments solutions. A group of larvae were fed with ascorbic acid treated feed only during the fifth instar. These treatments resulted in a significant increase in biological as well as economical parameters such as larval weight, female and male cocoon weights, shell and pupal weights ,and fecundity as compared with control. These enhancements were more pornounced in females than in males. 2% Ascorbic acid treatment increased the larval weight by 13.7% which was the most weight enhancement in the fifth day of the 5th instar larvae. This treatment resulted in 4.7% increase in cocoon's weight. The fecundity and egg weight in trated adult increased significantly, but had no effect on hatching percentage.
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