Abstract
A cytoplasmic-polyhedrosis virus was obtained from larvae of the fall webworm, Hyphantria cunea DRURY, which had infested plane-trees in the Tachikawa area, Tokyo, in 1966.Two types of polyhedra, one with nearly spherical and the other with tetragonal outlines were observed. The sizes of the polyhedra ranged from 1.2 μ to 3.9 μ in diameter and ultra-thin sections of the infected midgut showed the presence of spherical virus particles and polyhedra in the cytoplasm of the cylindrical cells. The virus particles were approximately 30 mμ to 65 mμ in diamter.The cytoplasmic-polyhedrosis virus of the fall webworm was not infectious to the silkworm, Bombyx mori, and the cabbage armyworm, Mamestra brassicae, but highly infectious to Spilosoma punctaria. The larvae of the fall webworm were susceptible to the cytoplasmic-polyhedrosis virus of the alfalfa caterpillar, colias eurytheme and the armyworm, Pseudaletia unipuncta.
