Although an infestation of rats can be temporarily controlled with poisons or traps, permanent control can only be achieved if food and harbourage are removed.
RATS WILL NOT ESTABLISH THEMSELVES IN AN AREA WHERE THERE IS NO FOOD OR HARBOURAGE ELIMINATE HARBOURAGE
Remove unused piles of lumber and debris. Lumber and firewood should be stacked on stands so there is 6 -8″ clearance below the pile and between the pile and any wall. Cut weeds and ornamental shrubs so that they do not hang into ditches or provide hidden runways along fence lines.
ELIMINATE FOOD SOURCES
Ensure compost bins are secured. Avoid leaving pet food outside overnight. Garbage bags should not be used for waste food disposal; where their use is unavoidable, the bags should not be placed outside until garbage collection day; metal cans with tight fitting lids are the only truly rat-proof containers. Bird feeders should be equipped with trays to catch spillage; spilled feed should be cleaned up immediately. Remove fallen fruit and nuts. Clean out accumulated wastes and food from pet enclosures.
The most successful and long-lasting form of rat control in structures is exclusion, or “building them out”. Screen crawlspace and attic vents (metal screen only). Seal all gaps/holes larger than 1/4″ around all doorways and plumbing fixtures. Repair cracks in cement footings and foundations and any openings for water pipes, electric wires, sewer pipes, drain spouts, and vents. For roof rats in particular, thinning dense vegetation will make the habitat less desirable. Climbing hedges and honeysuckle on fences or buildings are conducive to roof rat infestations and should be thinned or removed if possible, as should overhanging tree limbs within 3 feet of the roof. Separate the canopy of densely growing plants from one another and from buildings by a distance of 2 feet or more to make it more difficult for rats to move between them.