We have a problem with stray cats (looks like a mother and a couple of kittens) that like to crawl under and onto our deck. Our concerns; they knock over my Bonsai, they are not vaccinated for anything and are likely to be aggressive. I won’t approach them, given what I just said. I don’t want to harm them, but do want them to stay the heck away from my deck. We sprinkle out cayenne pepper, which repels them for a while. But it will wash or blow away, and they just come back, until we can re-apply it. Any other ideas to keep them away?