When I lived in California, I had persistent ant problems. I tried everything and the little bastards kept coming back. Sprays, borax, etc. One day, after I had doused my baseboards with the most “extreme” ant killer they had at my local hardware store, which left them crawling through oily residue since they refused to die, I took out a spray bottle of 409 to clean it all up. It killed every one of them, cleaned up the oil, dead ants and borax residue, and they didn’t come back. 409 is now my first choice for bug killer, but I question whether or not it’s a good idea for kitchen surfaces, because it is obviously toxic!
Actually, lots of poisons take time to kill, but are somewhat persistent, remaining effective for some time. One of the best and quickest killers is an ordinary soap solution. It coats their exoskeleton and suffocates them, but it requires direct application. They can’t just walk through it like some poisons.
Soap will kill squash bugs, and they are pretty much immune to most pesticides.