My apartment’s kitchen had roaches when I moved in. I bought a few commercial packages of roach baits. They contained both bait stations (which have poisoned roach chow in them) and a slow-acting fumigator type device that is supposed to destroy a roach’s ability to reproduce.
I left these items behind the refrigerator, behind the stove, etc. I strove to keep the kitchen extra clean. After a few months, and a couple of roach-bait packs, the problem had not lessened in the slightest.
One day, however, I watched a roach crawl down the face of my cabinets toward the floor. Instead of crawling down the baseboard between the cabinet and the floor, it dissapeared at the bottom of the cabinet. I checked, and there was a gap behind the cabinet and in front of the baseboard - a gap large enough to stick my hand through. The roaches were living in the enclosed space below my kitchen cabinets and above the floor. I had thought that this space was far better enclosed and that there was no hope of placing poison inside it.
I went to the store an bought another package of roach baits. I tossed most of them through the gap under the cabinets. I tossed in one of the fumigator things too.
The results were dramatic. I think it only took about 3 days for the roach sightings to drop off dramatically, and it was only about a week before I saw my very last roach. It’s been about a year since then, and I haven’t seen even a single roach, dead or alive, since.
My point here is this: It seems to be very important to put the poison in the right place. In my case, the roaches that I spotted were badly lost, and consequently, I put most of the first few packages of bait in the wrong places. If they killed any roaches at all, it was just luck that they did so. Putting them in the home base, so to speak, had immediate and dramatic results.
After reading some on-line material about roaches, I wonder if the cleanliness approach could possibly work. While it can’t hurt to keep the place extra-clean, roaches can survive on such tiny amounts of food and water that I, for one, wouldn’t really have a hope of eliminating them that way. My area is too humid to have a hope of getting rid of all the water, and my old apartment building is sure to have plenty of food (crumbs etc.) in the crevices from 40 years of previous tenants.
If there’s an enclosed space in your apartment that’s very difficult for light to get into, it’s a good candidate for roach HQ.
Good luck.