A new Bacillus thuringiensis strain, 00-50-5, exhibited an unusually high activity against banded sunflower moth (BSM) Cochylis hospes, which is an economically important pest of cultivated sunflowers in North America. The strain was fermented with a modified commercial medium in a bioreactor. This was a successful trial for production of 00-50-5 on a larger scale. After fermentation, the yield of dried powder was 5.8 g/l broth. In the laboratory assays, the LC50 (lethal concentration required to kill 50% of targets) of the dried powder was 0.5 µg/ml 3 d after exposure against four instars of BSM. Some practically useful conditions and parameters for the fermentation oper ating procedure and methods for harvesting were determined.