Pebrine caused by Nosema bombycis in the silkworm Bombyx mori L. causes severe economic loss to the sericulture industry. Several species of microsporidia and strains of N. bombycis have been isolated from infected silkworms. The study of the developmental stages of any parasite is important, as it leads to the identification of stages that may be susceptible to control measures. For this study, five microsporidian isolates from B. mori were collected from five different locations in West Bengal, India and a study of the developmental stages from mid-gut smears and histological techniques was undertaken. The observations of mid-gut smears and histological specimens revealed differences in the morphometry and duration of different developmental stages of the parasites.
