The Green Muscardine Disease in Silkworms and Its Control*

Abstract

During the summer seasons of 1922, 1923, 1924 and 1925, a number of the writer's stock silkworms died of a fungus affection. The disease invariably appeared during hot, humid spells, and unless controlled assumed epidemic proportions. The eggs, from which these silkworm cultures were derived, originally came from healthy stock, and since the fungus has been described as a parasite of a variety of insects, it must have been introduced by one of them. When the affection first appeared, the writer assumed that he was dealing with the so-called green muscardine disease caused by Metarrhizium anisopliae . In 1924 dead worms and cultures were sent to Miss Vera Charles, mycologist in the Bureau of Plant Industry at Washington, who definitely identified the fungus as Metarrhizium anisopliae (Metsch.) Sorokin, and also gave much valuable advice. The fungus belongs to the family Mucedineae , one of the Fungi Imperfecti; those forms in which the ascigerous or perfect stage has not been found