This summer, I had a problem with ants getting into my cat's food on his counter. I cleaned their paths to no effect. I used lemon and vinegar and all the various tricks that were supposed to deter or get rid of ants. Nothing worked. I don't like to kill unless necessary, but it become necessary because they were all over his food and it limited his eating time as he could only eat before the ants got to it.
Then I took inspiration from the Roman Empire, I think. I killed and beheaded ants and scattered the bodies near the edge of the counter where I believed they were coming up. I figured that might send a message to the ants.
They continued to come, so I continued killing ants, beheading them and scattering the heads and bodies on the edge of the counter.
After a few days, they apparently got the message. No more ants on the counter. And they've not been back even after I cleaned up the bodies.
I'm thinking the same sort of strategy could work with monkeys.
I had a similar experience years ago. I was using the bathroom sink once, and then a bunch of tiny ants suddenly started pouring out of the overflow drain hole. I was frozen in surprise for a few moments, having never experienced such a thing before or even imagined such a thing. When I had recovered my wits, I started methodically mashing them with my thumb. I actually killed them all just by doing that. No more ants, and they never reappeared.
As far as monkeys go, I hate the things. I suspect some of my hatred comes from movies and tv. The Nazi spy monkey betrayed Marion in
Raiders of the Lost Ark, and that sort of thing makes an impression on a kid. And I saw something on tv that involved a person trapped in a lab with a psychotic chimp, though I can't remember any more than that other than it scared the crap out of me. And then you hear news stories about some woman's pet chimp ripping her face off, and I've come to the conclusion that monkeys, chimps, baboons, etc. are a blight on the world.