Application of seven microbial pesticides to dust ducting method using hot air heating ducts was tested. The wettable powders (WP) of three Bacillus subtilis isolates were uniformly scatterd over greenhouse. Colonies of the B. subtilis IK-1080 were most frequently trapped on the nutrient agar plate in the greenhouse. Talaromyces flavus WP was also scattered over the greenhouse. On the other hand, Bacillus thurigensis WP, Avirulent Erwinia carotovora WP and Verticillium lecanii WP were not effectively scattered using the ducts.