Bacillus thuringiensis

tell me about this if you might know. its certified for organic gardening from some things ive read

You're talking about the spray, right?

I use a product called Thuricide. It is OMRI certified. When I see caterpillar holes in brassicas, I spray if there is no rain in the forecast. Only if I am seeing entire leaves disappearing. A few holes is acceptable. There are some folks that do not like any kind of spraying. I have a very small garden space and it is hard to keep enough greens to harvest if I don't spray sometimes. It doesn't help with aphids or other non-caterpillar critters. I just learned about Sawfly larvae this year. They look like caterpillars, yet BT doesn't do anything to keep them from munching away.

There are different ecotypes of Bt as well as the 'cry' toxins produced by them that act in insect control.  Please note the different known (and the list is expanding) Bt's in the section "How does Bt work" in the following link:   http://npic.orst.edu/factsheets/btgen.html