Empty a can of Vienna Sausages, except for the broth that remains. Leave it out, in the upright position, for your cockroaches. You will find that they crawl into the can and die, and so many victims there are. The question is why. They apparently do not attempt to crawl out because there are none dead on their backs. They're all face down. I looked at the ingredients: meat products, spices, and sodium nitrite. I don't know why it works but it's a great discovery!