Twenty two isolates of Bacillus thuringiensis (Berliner) (Bt) were, characterized from eleven different cropping ecosystems and evaluated for the pathogenic activity against Plutella xylostella (L). Based on the production of parasporal crystal eighteen isolates from present study and four previously isolated isolates were identified as Bt after examining the 212 Bt like colonies. Microscopic observations of crystal staining exhibited diversity as eight isolates were having irregular shape, six  of spherical, four both spherical and cuboidal, three with only cuboidal and one with bipyramydal shaped crystals. All the isolates that were found to be positive to V-P reaction, nitrate reduction, catalase production, casein hydrolysis, oxidase test and carbohydrate fermentation like, glucose, sucrose, trehalose test and negative for arginine hydrolysis and esterase activity. The isolates MDS-2, KMS-2, KMF, TNP, were found to be negative for starch hydrolysis while MDC, TNP, GTP for citrate utilization. Bt tested for their insecticidal activity against P. xylostella registered between 13.33 to 90.00 per cent mortality at 72 hr after feeding. Reference strain HD1 showed highest mortality of 100 per cent. While GBP-2, BGC-1, BGC-2, BGM-2 and KMP exhibited more than 80 per cent mortality.