On the original question about the soap and rubbing alcohol mixture, that sounds like something that would only work if you actually sprayed it on so it hits the bugs. Putting it on beforehand won't help at all.
Personally, I'd never spray rubbing alcohol on any plant anyway, no matter how much it was diluted. I've used it on a Q-tip to dab on mealybugs, but that's the extent of my use of alcohol on plants.
Soapy water kills a lot of bugs, but you have to actually hit them with it. It didn't help with my Sri Lanka weevils, though. They're another bug that hides under the leaves in the daytime and feeds on the plants at night - but since they're almost white, I got to them by going out with a flashlight once it got dark and just picking them off the plants by hand.
