When someone moved in my house a few years back, I got an infestation. Well I tried it all, And they still persisted! I researched, and found they are drawn to water. Kept all the surface's in the house dry... They still kept coming... Well to make a long story short. I had a sewer vent pipe on the roof that was leaking water right between the walls in between my kitchen and bathroom. I fixed that with some roof tar and they were gone a month or two later. Find where they are getting water from. Eliminate it... And you can finish them.
Unfortunately, some of the roaches didn't look for that bait. They must have been going through the "ventilation holes" in the kitchen. Houses built prior to 80s have those decorated holes which can be sometimes a bit funny. So, at most times, they would be on the wall. Luckily there are like four or five more being murdered by either me, the roach poison, or the trap. Flushing these out permenantly will be a tough thing to do. But I'll do my best.
Trin, you are right in that they are drawn to water but I don't think it's the water they need - I don't think they need much water to survive. But I think water makes things soft and easier for them to munch through stuff. The roaches in my house have chewed through two of my bathroom doors because we didn't keep them dry enough. Now, they are making it home sweet home, so we place the roach motels very close to their entry and exit points.
You can also take advantage of the fact they like water by filling a bowl with water. The Roach will climb into the bowl and then promptly drown.
Yes, it works well. You can use a jar placed next to the wall. The roach will climb in from the wall, but won't be able to get out. In drier climates just water will do, otherwise placing some coffee grounds in the water works.
Hmm.. That, I never knew. I think I will give it a try if I ever see more roaches. It would definitely save me a ton of money! I just "cleaned out" a batch of roaches 2 weeks ago. Took a few roach motels but the last one I left a week ago is still empty and open for business. LOL!