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Government Of Assam Handloom Textiles & Sericulture Directorate of Sericulture

Diseases of Silkworm

All varieties of silkworms are susceptible to various diseases caused by protozoan, bacteria, virus and fungus. The intensity of each type or diseases may however vary in different varieties of silkworm.


It is locally called Phutuka rog. It is the most serious disease in muga silkworm. In early stage heavy infection with pathogen spores, total crop failure in latter stage but sometime spin flimsy cocoon by the infected worms.

Causal organism: the casual organism is a protozoan, Nosema sp.

Route of infection:

  1. Through mother moth.
  2. Improper egg surface sterilization
  3. Feeding spore contaminated leaf
  4. Accumulation of faecal matter
  5. Contaminated rearing house & appliances
  6. Inadequate disinfection of rearing house & appliances


  1. Larvae loss appetite, Retarded growth, Unequal in size
  2. Body slightly shortened, becomes pale
  3. Black irregular pepper like spots on the skin

Control measures

  1. Effective disinfection of rearing house, appliances & equipments
  2. Effective egg surface sterilization
  3. Strict microscopic examination
  4. Proper sanitation & hygiene
  5. Avoid feeding diseased & fermented leaf
  6. Adoption of adequate prophylactic measure