If I were designing them, they'd thrive on the poison in the traps. Of course, if I were designing them, the cockroaches would be the focus of the experiment. I'd throw increasingly difficult challenges at them, culminating in some moderately clever primates. Once the cockroach Alpha arises, it would be saved for future study, and the rest of the experiment would be reset. That's the problem with an intelligent designer, isn't it? One tends to believe that they're the focus of the experiment. One tends to think that they will somehow qualify for special treatment. When, in fact, all that awaits you is euthanasia and a brain dissection. And that's if you're one of the lucky ones.