Norway Rats: Norway rats are most common along the sea coasts and canals. They thrive particularly in areas where garbage is not properly stored. Although Norway rats generally prefer to eat fresh meat, fish, and grain, they can survive quite well on an ounce per day of garbage or decayed food along with an ounce of water. Frequently they range 100–150 feet from harborage in search of food or water.
Norway rats are burrowers and often dig in rubbish and under buildings or concrete slabs. Burrowing can cause damage by undermining the foundations of buildings, eroding banks of levees, disfiguring landscape plantings, and blocking sewer lines.
They are reddish-brown and heavy-set with a blunt muzzle. The tail is about as long as the combined head and body. Adults weigh 3/4 to 1 pound. Their droppings are 3/4 inches long and capsule-shaped. Norway rats live about 1 year and reach sexual maturity in 3–5 months. They have 8–12 young per litter and up to 7 litters per year.
Roof Rats: Roof rats thrive in attics, roof spaces, palm trees, and ornamental shrubbery. They are climbers and prefer to nest off the ground. Roof rats are destructive to citrus groves since they live in citrus trees and gnaw on the fruit. They can be quite destructive in attics, gnawing on electrical wires and rafters.
Roof rats generally prefer vegetables, fruits, and grain; but they consume ½ to 1 ounce per day of food from various sources. Because they must have water to survive, roof rats also consume an ounce per day and will range 100–150 feet from harborage areas in search of water or food.
Color ranges from black to silvery gray to tan with a light belly. The tail is longer than the combined head and body. Adults weigh from ½ to pound. Their droppings are up to 1/2 inch long and spindle-shaped. Roof rats live about one year and reach sexual maturity in 3–5 months. They have 6–8 young per litter and up to 6 litters per year.
House Mice: House mice normally live outdoors in fields, occasionally migrating into structures. In houses, they live behind walls and in cabinets and furniture.
They prefer to feed on grains but usually nibble at a wide variety of foods. House mice require only 1/10 ounce of food and 1/20 ounce of water daily, surviving on food alone if it has high moisture. Frequently house mice range 10–30 feet from harborage areas.
House mice are brown to gray in color with the tail as long as the body. Adults weigh about 1/2 ounce. Their droppings are 1/8 inch long and rod-shaped. House mice live about one year and reach sexual maturity in 6 weeks. They have 5–6 young per litter and up to 8 litters per year.
How Pest Management works: A professional Pest Control Technician has the equipment and training to do a thorough job and has access to products not available over the counter. Below, is a typical approach to Integrated Pest Management (IPM).
IPM Approach for Rodents:
Rodent proofing: Rodent proofing is changing the structure of buildings in order to prevent entry of rats and mice. In considering rodent proofing, you must know that:
Rats can squeeze through cracks ½ inch wide; mice, ¼ inch wide. Any place a pencil can be poked, a mouse can go.
Rats can climb the inside of vertical pipes 1½–4 inches in diameter.
Rats can climb the outside of vertical pipes up to 3 inches in diameter and any size if within 3 inches of a wall.
Rats can jump vertically 36 inches, horizontally 48 inches, and reach horizontally or vertically 15 inches.
Rats can jump 8 feet from a tree to a house if the branch is 15 feet above the roof.
Sanitation: Good housekeeping or sanitation is a necessary factor in rodent control. Eliminating food, water, and harborage for rats and mice can reduce rodent populations rapidly.
To implement sanitation practices:
Clean up garbage and rubbish.
Properly store garbage (Metal garbage cans should have tight fitting lids).
Properly store food (store raw or prepared foods and refuse indoors in covered, rat-proof containers or in rat-proof rooms).
Store pet food and bird seed in rat proof containers.
Remove harborage (remove piles of rubbish, trash, junk, boxes, and protected enclosures).
Dry up sources of water.
Pick fruits and vegetables when ripe so rodents will not feed on them.
Trapping: Trapping is an underrated method of controlling rodents. One reason trapping is often overlooked is that snap traps have been around for a long time and are cheap. Traps can be used to eliminate rats where poison baits would be dangerous, to avoid dead rat odors, and to eradicate bait-shy rats.
Glue boards: Special glue can be placed in pie tins or paper plates. The glue does not harden but will hold a rat in place. Other rats become curious and also get caught. Placing a small piece of bait in the center of a glue board can increase effectiveness. Dusty and wet conditions will impair the trap's effectiveness. Glue boards are better suited for mice and safe for children and pets.
Poison Baits: Traps are effective usually when dealing with small numbers of rats or mice. When rats are plentiful or where unsanitary conditions exist with harborage, poisoned baits are an effective tool to use with trapping.
How can you help: Improving sanitation by eliminating food and water sources and clutter can have a significant impact on reducing the chances of infestation population size. Finally, exclusion practices such as rodent proofing will reduce harborage spaces and also negatively impact population size.