Secondary kill is when insects that did not feed directly on the bait still die. The mechanisms used by German cockroaches are coprophagy and cannibalism. With coprophagy, adults eat the bait, return to the harborage and defecate. The feces is contaminated with toxicant from the bait. Relying on cannibalism for secondary control is also effective.
Cockroaches eat the toxic bait and return to the harborage.
While they are dying and can't defend themselves, other cockroaches eat the contaminated roaches, or later eat their carcasses. As a result, the cannibalistic roaches also die, and the cycle continues. Baits were tested to see if secondary kill could be attained through cannibalism. Fipronil, boric acid, abamectin, hydramethylnon and chlorpyrifos were included in the test. The varying materials were placed in jars with second-stage nymphs until the nymphs died, and then they were fed to adult roaches.