Yes, BT will kill all kinds of caterpillers. If you use that, you don't have to worry about washing off pesticide.
Please google the proper use of this product, don't take my word for it that it is safe. The powder I've used, btw is 0.25% permethrin. I have thoroughly washed any vegetable I...
This is the first year I have used permethrin powder on the garden. It is an insecticide also sold for poultry. I used it last year to control mites on a hen and her day-old chicks and it was effective and seemed safe. This is the same insecticide used in lice medicine for humans.
Anyway, it...