I understand, we get Tussock Moth caterpillars every spring and some years they are so bad I have to spray. I kill them by hand if I can, but when things get too bad, I use BT spray. It's short for bacillus thuringiensis, a naturally occurring bacteria that caterpillars ingest and then die. It's organic since it's a bacteria that normally exists in the wild, anyway. Just make sure to only spray it on the affected plant so you don't harm any other caterpillars that you want in your garden!
