Can isopropyl alcohol alone keep away household pests e.g. cockroach, rats, worms and other pests commonly found indoors? Do they fear alcohol? I don't like using pesticides but I like using 75% alcohol to clean things.

It's not very efficient as a pest deterrent, and can be very dangerous.

On 2/9/2023 at 7:49 AM, Phi for All said:

It's not very efficient as a pest deterrent, and can be very dangerous.

Why is it dangerous?

It's flammable, and the vapors are denser than air. It will definitely deter or kill certain bugs if you use a lot of it, but higher concentrations pose higher risks of combustion. Don't use it around wood or leather. Keep it away from bleach. 

It's probably keeping some bugs away the way you're using it now. If you still have bug problems, you should look for a solution other than increasing the amount of alcohol you use. 

Also it evaporates rather fast, making it rather useless (and dangerous) as a deterrent.