Many people want to know how to kill rats, but the reality is that killing the rats may not be the best solution to a rat infestation problem.Rats are a nuisance species for many reasons. Most residents and business owners overlook the noise, scurrying and scratching until the rats break into the living space and start to chew on and contaminate food items in the house. The most obvious sign of a rat infestation is the presence of dead or living rats. Rats prefer to hide, given enough space, so if rats are observed in plain sight, it is likely that a full-blown infestation already exists. When space becomes limited due to increased population, rats are forced out into the open.