few days, so repeated applications may be necessary.   http://www.greenharvest.com.au/pestcontrol/ca terpillar_prod.html http://en.wikipedia.org/wiki/Bacillus_thuring iensis Bacillus thuringiensis is a Gram-positive , soil dwelling bacterium of the genus Bacillus . Additionally, B. thuringiensis also occurs naturally in the gut of caterpillars of various types of moths and butterflies , as well as on the