I can offer two suggestions for outdoor use on wasps and flowers. We had a growing problem with wasps that had setteled into a space under the roof overhang on the deck and commercial spray was effective for maybe a day and cost way too much for continuous spraying. A neighbor told us about the use of filling your sprayer with a heavy solution of water and detergent and spraying it as needed. Husband started in the middle of summer last year and narrowed them down but not out. This year they are gone. He sprayed them every time they came out but kept at it and for the first time in several years we are wasp free. The other thing is coffee grounds. I had read recently about using them in a variety of ways but was most interested in outdoor plants. I started putting the grounds in a large coffee container and when it was full I scooped them on to the petunias and other flowering areas, as well as rose bushes and hydrangeas and they are all, except the roses, the most beautiful blooms we have ever had. I continue to save the grounds and use them routinely. We try anything that seems to have potential and always open to new ideas.
No more wasps of either kind around now for 2.5 years. A little pricey, but after walking over a yellow jacket nest and getting about a dozen stings, I didn't care.