Hello, VaryaV! May I ask what city you are in, or near? Just wanting to know where kindred souls are here in FL. This AM suffering 80% RH. I spent 35 years in the west and came back to FL to take care of my old parents. My greatest nemesis is humidity. I hate it!
Yes, many, many good suggestions. A dehumidifier will cost less to run than A/C. Of course, you might want or need that A/C anyway. I have noticed by watching my hygrostat after I turn the A/C on, that the RH goes down first, then the temperature.
On my arrival here 15 months ago, there were roaches to be seen all of the time, everywhere. It's not that my parents are pigs, but Dad long ago stopped working on things around the house, including insect control. I appear to have been successful, with only the very occasional roach appearing, either dead or alive. As someone noted above, most of mine lately have been small-ish. No giant honkers. I hereby confess that no doubt I was assisted by my 35 year old bottle of Chlordane, best stuff ever, now illegal to make, sell, use in agriculture, but not to own.
If you go the boric acid route, you can find big plastic squeeze applicator as insect control inexpensively. Don't buy a little bottle at Walgreens!
There are white pellets you can buy "anywhere" in a yellow box with brown lettering. Harris Famous Roach Tablets, I think. I deployed them a year ago under and behind applicances, cabinets, closets, behind book cases, under the sinks, by the garbage, and so on. I really think that these are a major component of my success.
As to sprays, I have determined that some are really good at an immediate kill and others may or may not do that, but have a long term staying power. I've recently successfully used Ortho Home Defense Max for sugar ant control after sprays of the first kind did nothing. Supposed to work for roaches, too.
This is my hygrometer:
http://search.harborfreight.com/cpisearch/web/search.do?keyword=hygrometer&Submit=Go I think it is fairly accurate; nothing will be as accurate as a sling psychrometer. Don't bother with the little equivalent from Wart-Mart for $7. As the humidity is either higher or lower than 50%, the error increasingly, uh, increases.
Just don't do what my mother did. She grew up in Brazil. One night she flips the light switch on and a giant flying roach was aiming right at her. She opened her mouth in reaction to scream, then too late realized that was a stupid thing to do. Bit the roach in two........... One of the great family stories. She would tell it to her kids when she was a teach way back. Recently met a woman who was one of those kids 30 years ago and her most vivid memory was the roach story.