TOP ELEVEN PEST- ROOF RATS
The roof rat is the smaller of the two commensal rats (Norway is the larger) and the more common commensal rat in the subtropical and
tropical regions of the world. It does damage by gnawing, eating and contaminating stored food, and as a vector of disease organisms.
Identifying:
Adult roof rats have a total body length of 6-8" and a tail length of 7-10", and weigh up to 12 ozs. The color is usually
brown with black intermixed, but can be gray to black on top and white gray or black underneath. They have a pointed muzzle,
large eyes, almost naked ears that are so large they could be pulled over their eyes. The tail is scaly and longer than the
head and body combined.
Infestation Signs:
1. Gnaw marks. New gnawing tends to be rough, while old gnawing tends to be smooth from wear.
2. Droppings. Fresh droppings are soft and moist, about ½" long with pointed ends, old droppings are hard and dry.
3. Tracks and or footprints. Front foot has 4 toes and hind foot is bigger with 5 toes. Fresh tracks are clear and sharp.
4. Dark and greasy rub marks on vertical surfaces. Fresh marks are soft and greasy and easily smeared whereas old marks are
dry and flaky.
5. Burrows. These are not common, but if they are present they will be shallow. They usually nest in high places like trees
or in or under vegetation.
6. Runways. Outside, travel routes are not so apparent because they often travel along fence tops, and phone and power lines.
Indoors they move along walls, ...>> back to top
stacked merchandise, etc. Active runways will have a greasy appearance, be free of dust/cob webs, and have fresh tracks/droppings.
7. Damaged goods. Rats prefer fruits, vegetables and cereals.
Habit:
Roof rats are primarily nocturnal in habit and they are very cautious. Although they constantly explore their surroundings, they will shy away from anything new. They are social animals so several nests may be found in a given area. They can enter a building through an opening of only ½".
Once established indoors, they will follow the same path from harborage to food and water, every day. Once they find a food source they like, they will eat their fill at one sitting, and return time after time.
| Signs gnaw marks, droppings | Signs footprints, burrows | Signs damaged goods, runways |
Biology:
Roof rats reach sexual maturity in 2-5 months. Pregnancy lasts an average of 22 days. The young are blind and naked at birth, with
hair appearing in about 7 days and eyes opening in 12-14 days. They are weaned at about 3-4 weeks. The average number of litters is
4-6 per year, each containing 6-8 young. Adults live an average of 9-12 months.
They have fairly poor vision and are color blind, but their other senses are keenly developed, with touch coming through their
whiskers. They are good runners, excellent climbers and jumpers, and if forced, fairly good swimmers.
Roof rats are vectors of several diseases, including bubonic plague, murine typhus, infectious jaundice/leptospirosis/Weil’s
Disease, trichinosis, Salmonellosis, and rat bite fever.
Control:
The first steps are ALWAYS identification, sanitation and harborage elimination, and rat proofing the building. Control is then based
on the behavior of the rats. Methods of control can include baits, and or traps. At Arizona Organic, we prefer traps because they can
give a faster result with less chance of causing an odor problem from rats dying where they can’t be retrieved.>> return to TOP ELEVEN PEST
