The present work monitors the growth parameter and cocoon production in Bombyx mori fed on V1 mulberry leaves fortified with the putative probiotic bacterial, Lactobacillus casei. The growth of (length and weight) the bacteria supplemented silkworms of the all instars (II-V) increased significantly over the control animals. The maximum body length (55mm) observed was in the probiotic supplemented worms of the IV instar, while the control worms at IV instar could attain only 46mm. The body weight of probiont supplemented II instar larvae showed a three-fold increase (689mg) compared to the normally fed larvae (205mg). In the fifth instar larvae, the probiotic supplemented group recorded a very high body weight (3550.0mg) than the control group (2946.0mg). Weight of the cocoons from worms reared on probiotic bacteria was higher than that of the silkworms fed on mulberry leaves alone.