Once rats have moved indoors, especially in residential structures, people tend to become aware of the unwelcome guests quickly. Depending on the species, the rats will move into wall voids, attics, basements, cabinets or storage rooms. While they do not usually inhabit occupied rooms, it is possible, so all rooms should be inspected. There are several signs of a rat infestation to look for indoors:
- Droppings - Rat feces or droppings are brown, cylindrical pellets that are usually about 1/2 -1 inch long and about 1/8" in diameter.
- Urine - Rats urinate frequently and the urine has a pungent, musky odor. This will be most noticeable in the rat nesting area.
- Grease or rub marks - Rats like to travel with one side of their body rubbing against a vertical surface and since they travel the same path again and again, over time a greasy grey mark will be left behind. You should look for these marks on beams, rafters, baseboards, bottom of door frames and other areas where suspect activity.
- Gnaw Marks - Rats teeth grow quickly as they constantly gnaw on hard objects usually to gain entry to new harborage areas or in search for food. Look for wood and pipes that show indications of gnawing.
- Squeaking or gnawing sounds - While rats like to hide as much as possible they are rarely quiet intruders. When rats socialize they squeak quite a bit. Their gnawing activity can usually be heard as well. Following the sounds can help locate the nesting areas. Listen for noises from suspected nesting areas just after dusk.
- Food tampering - What do rats eat? Rats are scavengers and will eat most foods they can get access to, including fruits, vegetables, grains, meats and pet food. Rats will gnaw through food packages to obtain the food inside. Check food packages in pantries and pet food containers for evidence that rats have gnawed into the package or otherwise tampered with the food.
Rat urine is fluorescent and is visible under a blacklight. Pest control professionals frequently use a UV flashlight to help detect rodent urine. You can use this technique to see if rodents have been in your cabinets or other areas where you need to inspect.