An investigation was conducted to study the diversity of entomopathogenic bacteria Bacillus thuringiensis, in rice ecosystem in UKP area Karnataka, India. Survey was conducted to collect soils from different places and Bacillus thuringiensis were isolated. Totally 72 B. thuringiensis isolates were collected from  the survey. The cell sizes of the B.thuringiensis isolates varies from 1.45×0.83 µm  to  3.49×0.63 µm, where as  endospore size varies from 0.83-0.66 µm to 1.66-0.66 µm. Among collected bacteria  64 % of the isolates produced bipyramidal crystal  shape and  3 % produced triangular shape, 9 % produced bipyramidal and triangular shape, 9% produced spherical,  2 % produced  ovoid and  2% produced triangular and bipyramidal shape. The pathogenicity of isolates against 2 ^nd instars Diamond back moth larvae  showed, mortality ranged from 0 to 100 per cent. Bioassay showed that LC₅₀ value was minimum in Thanegundi isolate (1.9×10^-4) followed by Karkalli, Yevur and Gogi isolates.