We do not know exactly from how far rats will be able to smell a lure or other food source, however we do know that about 1% of a rat's genes are involved in their sense of smell, so they have a far more advanced and keener sense of smell than humans. Norway rats and roof rats easily will travel 90 feet or more from their nest for food and water, but they also will return to the same sources until their dietary needs change, the source is no longer available, or they discover a more accessible and desirable food source. The Propest Rat and Mouse Lure may not be able to compete with other existing food or water sources in an area, so it is important to use other control methods in conjunction with your trapping. A good trick when using a lure on snap traps is to place the lure on the traps for a few days first without setting the trap; this allow the rats to discover and learn to trust the food source. Then, when you set the trap with the same lure, you are much more likely to catch the rats.  Please see our Rat Pest Guide for information about how to best Identify, Inspect, Treat, and Prevent rat infestations. If you are careful to seal up entrance points that rodents would have into the house, then you can limit your indoor control needs to the rodents that are already there instead of new ones entering from outside. We would also recommend using tamper-resistant bait stations and a good rodenticide outside around the structure, such as those found in our Rodent Baiting Kit. Please let us know if we may further assist you.