The Surprising UX of Rat Poison

One of the structures on our farm has a rat problem. They're chewing through the plumbing and the results have been disastrous. The exterminator we hired examined the site and let us know it would be cheaper to solve the problem ourselves, as it requires distributing rat poison in the crawlspaces every week, until all of the rats are dead. I asked him how we would know that we got them all, and he shared this interesting piece of information: All rat poison is required by the EPA to be...