Silkworm Bombyx mori L. are affected by major diseases, such as grasserie, flacherie, muscardine and microspordian. White muscardine disease is most dangerous, virulent in silkworm and mainly caused by entomo-pathogenic fungi Beauveria bassisana also named as mycosis. Low temperature and high humidity plays a big role in the occurrence of muscardine. Pebrine disease is a chronic condition in silkworms caused by a microsporidian. It is transmitted to the offspring through transovarial transmission from the mother moth. Grasserie, a viral disease, can be observed all year round, but it tends to be more severe during the summer and rainy seasons. Flacherie disease is caused by various bacteria such as Streptococcus sp., Staphylococcus sp., Bacillus thuringiensis, and Serratia marscesence. These bacteria are responsible for the onset of the disease.