Boric acid is commonly used in detergents, fertilizers and hand soaps. It is also used as an eye wash, and is found in apples, bananas, nuts and even beer. But one of the major uses of boric acid is for control of cockroaches.
When cockroaches come into contact with boric acid powder or dust it clings to them. Later when they clean themselves, they ingest it and it acts as an insecticide. Ants and mice are other pests affected by the toxicity of boric acid.