Roof rats get their name because they tend to be found in the upper parts of buildings. They are also called black rats or ship rats.
Where do they live?
Outdoors, they nest in vegetation, shrubs, and vines which are above ground. They do not nest underground in burrows. Indoors, they build nests in the upper areas kept warm by rising heat—cabinets, ceilings, garages, inside walls, laundry rooms, patios and pool areas. They are good climbers and generally enter buildings from overhanging trees or power lines.
How do they live?
Females can have as many as 3 to 6 litters of 6-12 pups per year. They live in colonies and are nocturnal. They forage for food in groups and tend to return to the same food source time after time.
They mainly eat nuts and fruits, but will eat just about anything if they are hungry enough, including: ornamental plants, pet food, chicken feed, vegetables, tree bark, insects, lizards, paper, and candle wax. They stash nuts and seeds in their nesting areas for later use.
Their living space must provide them with enough water to sustain life. Water sources for roof rats include: bird baths, leaky pipes, air conditioning condensation drip line, pets’ water bowls, saucers under potted plants, and irrigation lines.
They will chew through plastic and metal pipes to get water. All they need to get into your home is an opening about 12.7 mm (1/2 inch) to squeeze through.
How do they affect us?
Roof rats can spread diseases such as typhus, jaundice, rat-bite fever, and bubonic plague. The rats can show aggression if they feel threatened and they may bite or chase you. Their droppings and urine can spread disease.
They can chew on wires and water pipes which may lead to electrical and fire hazards and water damage respectively.
How do we control them?
Bushes near the house should be thinned out to prevent rats from using them as cover. Trees and shrubs near buildings should be trimmed and limbs overhanging the roof should be cut. Any holes or cracks measuring 1/2 inch or 12.7 mm or larger should be sealed. Entryways under sinks, near washers, dryers, dishwashers & hot water heaters should be blocked and doors should also be shut when exiting the house. All window screens ought to be kept in good condition.
All fruit fall should be removed and garbage ought to be placed in tightly covered receptacles. All water that can be used by the rats should be eliminated.
Baits, snap traps, and glue traps can also provide some measure of control.
Learn how to identify common pests; understand their biology, diet, and habits; and find out what you can do to control them.