What else can I do to stop this cat coming into my house....

[LivinLaVidaLoki]

We have a cat. There are several cats in the street but there is one (non neutered) cat that was constantly getting in our house, fighting with our cat and peeing everywhere.
We installed a cat flap. One that works by reading our cats microchip. A few times this cat has been thwarted at the door.
However it has now managed to get in by literally being on my cats tail as he chases him in. He has got in and ran into one room straight to the window, tangled into the blinds and wrecked half of them trying to escape. He almost just made it in again.

I am at my absolute wits end. I spoke with the owner a couple of weeks ago (pre blind damage) and she said she was going to get him neutered last week as he wanders too far, just disappointing she won't be able to breed him.

So either he hasn't been neutered or its not slowing him down. Either way how on earth can I stop this???

Is he a stray? If so take him to a rescue or adopt him and get him neutered. Otherwise no suggestions sorry!

Pump action water pistol with water and citronella oil in it!

Grumpypersonwithcats might be able to advise!

If he has owners that are so irresponsible that they are letting an un-neutered male out to raom, then take it to a shelter and declare it as a stray. They will either neuter and release as a feral cat (unlikely if its tame) or neuter and re-home.

I doubt they have it micro-chipped if they havent neutered the poor boy.

For now I would lock the cat flap and have your cat ask to come in and out.

Neutering him this late won't make much difference, I'm afraid. My beloved cat (long departed) was a rescue and neutered late and sounds exactly the same as your unwanted visitor. He was mostly lovely at home but terrorised my neighbour's poor cats.
I gave her a big water pistol and told her to soak the blighter every time he came near her door, and really drench him if he made it inside. She did and he stopped trying after a few weeks (he was a slow learner).