The extra-fine filament is size of cocoon filament below 2.0 denier in silkworm. "Hakugin" is known as the extra-fine filament silkworm race. However, in recent years, because the size of “Hakugin” cocoon filament is becoming thicker, the development of silkworm races has been required in order to maintain its extra-fine filament. And improvement for oviposition properties has been demanded from the viewpoint of silkworm eggs production. On the basis of parent strains of the “Hakugin”, we were grown new strains with improved properties of cocoon filament and oviposition, “C516 × C517”. As compared with Hakugin, this breed didn't change any of the fineness, yarn quality and so on. In addition, this breed, it was better the oviposition properties than “Hakugin”. “C516 × C517” was conducted a trademark registration nicknamed as "Hakurei".
