Experiments were carried out at the vivarium of the Silkworm Experimental Station in Vratsa during the autumn silkworm feeding in 1980, using the Kinshu x Showa hybrid. Tested was its tolerance of a water solution of chlorinated lime with active chlorine from 0.003 to 1.0 per cent administered orally with the feed. Studied was at the same time the inactivating capacity of these chlorine solutions with regard to 0.3 per cent water solutions of dipel in less than a minute's time, the latter being sprayed over the leaves of mulberry trees 24 hours prior to giving the leaves to the worms. It was found that the silkworms tolerated well mulberry leaves sprayed with water solution of chlorinated lime of active chlorine ranging from 0.003 up to 0.4 per cent. Rates of 0.06-0.07 per cent active chlorine could inactivate dipel in 0.3 per cent solution. It is believed that aqueous solutions of chlorinated lime of 0.06-0.07 per cent active chlorine could be used in the inactivation of dipel in concentration not higher than 0.3 per cent when the preparation is sprayed at the rate of 100 cm3/m2 in mulberry plantations in the period of growing.