The insect pathogens Bacillus sotto Ishiwata and Bacillus thuringiensis Berliner can be differentiated by means of certain cultural and morphological differences, and by a quantitative difference in pathogenicity for the larvae of Bombyx mori L., B. sotto being the more pathogenic. They are also pathogenic for the larvae of several North American Lepidoptera including Anisota rubicunda (F.), Anisota senatoria (A. and S.), Nymphalis antiopa (L.), Erannis tiliaria (Harr.), Datana integerrima (G. and R.), Datana ministra (Drury), Liparis dispar L., Protoparce quinquemaculata (Haw.), and Protoparce sexta (Johan.). Silkworm larvae ingesting material from a sporulated culture of B. sotto become sluggish, cease feeding, and suffer from a progressive paralysis that begins in the mid-gut area, spreads to affect the whole larva, and ends in death.
