Polyhedrosis of the Silkworm

one of the most dangerous virus diseases of the caterpillars and pupae of the Asiatic and oak silkworms.

The principal source of the spread of the causative agent of polyhedrosis is diseased caterpillars. Mass death of caterpillars from polyhedrosis is most often observed before the beginning of cocoon spinning. The body of a diseased caterpillar is greatly distended and somewhat shortened; its integument tears easily, and a muddy hemolymph is discharged from the body. When the caterpillar dies during pupation, the cocoon does not give forth the customary knock when shaken (a so-called dead cocoon). There is no specific treatment. Prophylaxis against polyhedrosis of the silkworm includes periodic disinfection of premises and implements, feeding the caterpillars a diet rich in carbohydrates, and maintenance of optimal humidity and temperature during rearing.