What object or food that is poisonous for cockroaches?

Boric acid is a commonly used substance that is poisonous to cockroaches. When ingested, it disrupts their digestive system and eventually leads to death. Additionally, diatomaceous earth, which is made from fossilized algae, can be harmful to cockroaches by damaging their exoskeleton and causing dehydration. Both substances are effective in controlling cockroach populations when used properly.