Well I finially have a solution for the wasp eating us out of house and home. Use a 12.5 ounce can of Swanson's white chicken breast meat, and 1/2 teaspoon of Taures SC insectiside. I would love to post the vidio, but not techy enough! The idea is to get the wasps to carry the poison back to their nests, thereby eliminating the whole colony. Use a cage when putting out, so you don't poison the birds, and local wildlife, something that lets the wasps in but keeps your cats and dogs out as well. It works better that anything else that I've used, with no spraying poison on your grapes. Wish I had known of this years ago, it'll put a hurtin on the wasp population.
I had been spraying Malithion on my grapes, and while it did the job, it washes off with every rain, and has to be reapplied. Plus you have to wash your grapes when you pick, which is another pain in the pooper!