Get some Dipel on there when they are small. Active ingredient is BT. For those mash all you can.

or flick into soapy water.

Early instar Grape Leaf Skeletonizer moth caterpillar. BT can be effective for this pest.

How long does it take to work? I sprayed it on them and they seemed unaffected at the time? How does it work on them? They don't seem to be repelled at all. Another problem is it continues to rain every afternoon and I'm afraid it's washing it off. I'm spraying it back on every day it rains.

They need to eat the stuff. I think it paralizes the gut. Doesn't work immediately, a day or two. It works better the younger the worms. Next yr get it on earlier.

Errrrrrrr, pretty bad worms, but actually try a mixture of garlic juice, soap, and Chilli pepper, it may sound strange but bugs don't like it, it's more natural to.