Irony is that the American, german and oriental cockroach are all african in origin...
Orientals are the worst... scarred me as a child.
They love the moist, dark area. Try to eliminate that - alter your enclosure so that they're less comfy. In other words, put roach traps there.
At the very least, you kill some of them.
I can't tolerate roaches (that I don't specifically order off the internet and put into plastic bins). They just ruin my day. Again, the big, black oriental roaches of Northern NJ... those are the worst. If I could have an entire species go extinct by the push of a button, it'd be them.