Commercial FI hybrid eggs (seeds) of silkworms procured from Japan and Korea, were subjected to self crossing for seven generations during 1977 to1983 at Sericulture Research Laboratory, Lahore. The pure strains of Japanese, Chinese and European races separating as a result of their segregation, were picked up on the basis of their respective racial characteristics. The pure lines of Japanese, Chinese and European races, so obtained, were given the following names.