Wow Lyn, I never even thought to ask if the hornet spray could hurt the plant. We spray well after dark so as to make sure the hornets are all in the nest, and then we cut out the whole branch with the nest the next morning. Spraying after dark is a way to assure no bees are affected also. So I guess it does hurt the plant in the sense that I am cutting a section of it out in order to remove a sprayed nest!!!
I am terribly allergic to most stinging insects. I couldn't use my right hand and arm for 2 weeks last summer after 1 sting. My knuckle was severely bruised when we removed my ring right after the sting, before much swelling had started. Even though I'm strongly anti-chemical, pro-critter, I don't want to have to use the epi pen ever again. We have 4 honey bee hives, various wild bees, mud daubers, wood bees, huge cicada wasps, and all of those agree to coexist peacefully. We have some black and blue wasps and hornets that are downright aggressive. You can't get anywhere near their nest without being attacked. The yellowjackets here at least have to be provoked before they attack. Not so with our hornets. I'll look for my insect book where I marked the exact ones that were a problem, see if I can come up with the correct names.