Hi this is my first time growing and i have a three foot purple urkle in my back yard , its done great until recently i noticed a couple of caterpillers , it has been blooming for four weeks now and am planning to harvest some time in early oct is it to late to use bt or should i just keep picking them off? i am afraid they will take over and it looks great , it is very sticky and pungent i feel it may be to late , PLEASE HELP....