it’s somehow re-jiggered its taste system so that the attractant that humans used to draw the insect to poison bait—the sugar glucose—now tastes bitter to the roach, and they avoid it. cockroaches began appearing that avoided the baits, and did so not because they were averse to the poison, but because they were averse to the attractant, glucose. This new trait turned out to be heritable, that is, it had a genetic basis.