Sustainable methods of cockroach control (Periplaneta americana)

Question

A second significant pest issue we have here is that of the so-called American Cockroach, which seems to normally live outside near human activity and come inside at least a few times a year. Currently we control these with periodic, carefully timed insecticide application (this cockroach has a slow growth cycle so right now that means 3-4 times/year, 2-3 applications per time). We spray heavily in bathrooms which have little ventillation, let sit for hours, and then open up to ventillate. This seems to work but I don't like the implications of using pesticides in this way or manner.

We believe that the pests enter from outside, and climb into the pipes from the drains in the back garden. Because of the setup it has not been particularly possible to put screens on those drains with small enough holes to discourage these pests. Additionally they may wander in the front door (I am not kidding, I have seen this) and then scurry around until hidden, waiting until later to find drains to crawl into.

What additional means are there to control/prevent infestations of cockroaches? I suspect that this species is likely to be the easiest to get rid of, of the cockroaches, because despite the fact that it runs fast and that the adults can fly, it takes 6-12 months for young to reach sexual maturity (a bit over 4x the time the German Cockroach requires). I would assume then that methods of controlling other cockroaches might be effective here.

It is worth noting I have not seen any evidence that they are in our food (we do have geckos but that's another story, and the problems there are simply prevented by being careful about keeping food containers closed). As far as I can tell the activity is entirely limited to the drain pipes, which go from the septic system (yes, everyone in Jakarta has a septic system) to things like the shower.

Edit: as a side note I have considered trying to introduce geckos to the drain pipes. Not sure how well they would fare there though and that might be cruel so for now I have ruled that out.

Answer 1

If you can maintain good hygiene in the kitchen (so there's little they can eat in there that will help them breed) then glue traps may be effective enough to keep the population low. I keep a couple of them on the top of the kitchen cupboards, and the cockroach population seems to be under control despite using no sprays whatsoever.

Answer 2

Those cockroach are unable to exit from an aluminium can. The only problem is to get them in.

1. Cut open a can

2. Paint the outside with anything that would give foot traction. You can also glue some paper

3. Put some bait inside. Stale beer is possibly the best. Any leftover would do.

It is not nearly as efficient as chemicals as those are designed to poison the colony itself. But spreading several of those inexpensive and low-maintenance trap would work.

Of course, it means that you would have dozen of starving roaches scratching the wall of their aluminium prison at night. I can live with it, but you may wish to put some water inside to drawn them. Just know that an apparently drawn cockroach could revive within minutes while out of the water. Rule #4: double tap