This OMRI-listed and compliant for use in organic gardening pest control product is very effective in killing caterpillars and worms, including corn earworm, bollworm, and more than a dozen other types of worms! This garden dust with BT. utilizes bacillus thuringiensis (var. kurstaki) which, once ingested by the pest, kills them within a few days. It is recommended that this product be applied late in the afternoon or on cloudy days since BT. breaks down in the sunlight.