The Norway Rat and the Roof Rat are the two most common rats that invade homes and buildings in the U.S. Following are some common questions and answers about these destructive rodents.
Q. How do I know if I have rats?
A. Because rats are nocturnal and are most active at night, an infestation can develop before a rodent is ever seen. For this reason, it is best to keep an eye - and an ear - out for signs of rodent presence. These include:
- live or dead rats.
- droppings, especially around human or pet food or in or around trash areas.
- noises in the dark, such as scratching sounds from the attic.
- nests or piled nesting materials in hidden areas.
- evidence of gnawing of wires or structural wood.
- burrows around the yard; under the home or outbuildings; or gnawed fruits in trees.
- smudge marks along walls or rodent hairs along paths, in nests, or near food.
Q. How do I know if it is rat, not a mouse?
A. Averaging 9 to 11 inches long plus tail, rats are much larger than mice. Rat droppings are 1/2 to 3/4 inch in length, whereas mice droppings are only about 1/4 inch.
Q. What do rats eat?
A. Rats will eat just about anything, but they prefer grains, meats and some fruits. Rats will eat about 10 percent of their body weight every day.
Q. How long will a rat live?
A. Rats generally live about a year, but can live much longer in ideal conditions.
Q. I think I found a rat nest, but it is in my attic. Would rats really be there?
A. Roof rats, as their name indicates, usually nest above ground in trees or tall shrubs, so their indoor nests are just as likely to be in upper levels of the home. Roof rats are very good climbers and often access homes by running along tree branches, cables or wires.
Q. Where should I put rat traps?
A. Traps should be placed where the rats are. Look for signs of nesting, gnawing, and droppings. Place the traps right up against the wall in secluded areas where they are seeking shelter and along the runways and trails the rats are traveling.
Q. I know I have rats, but my traps aren't catching them!
A. Rats can be wary of new things and if one sets off a trap but is not caught, you are highly unlikely to get a second chance. For this reason, it can be advantageous to place unset, baited traps first. Then once the rats are used to them, rebait and set the triggers on the traps.
Q. What is the best bait for rat traps?
A. Contrary to popular belief, cheese is not the best bait to use on traps. Dried fruits, unshelled nuts, or even pet food can be attractive to rats. Be sure to attach the bait to the trap so that the rat cannot remove it without springing the trigger. This can be done with thread, fine wire or even glue.
Q. I think I have rats, but I never see any. Why not?
A. Rats are nocturnal creature, so they are most active from dusk up 'til morning light. If rats are seen during the day, it is generally an indication that the nest has been disturbed, they are seeking food, or there is a large infestation.
Q. Why are one or two rats a problem?
A. In a single year, one pair of rats can lead to the reproduction of more than 1,500 young, because rats as young as three months old can breed and produce offspring. A female can have up to 12 offspring in each litter and up to seven litters in a year.
Q. How do mice get in my house?
A. Rats – both the young and the adult – can slip through 1/2-inch holes and gaps - much smaller than appears possible. They will also gnaw smaller holes in order to make them large enough to squeeze through.