Rodents

DID YOU KNOW..... The word Rodent means: to gnaw?

Rodents have in both jaws a single pair of incisors with a chisel-shaped edge. Without continuous gnawing, their incisor teeth would grow right through their jaws!

Rodents are nuisance pests entering Florida homes and warehouses for food and harborage. These rodents eat any kind of food that people eat. They also contaminate 10 times as much food as they eat, with urine, droppings and hair. They can carry at least 10 different kinds of diseases including bubonic plague, murine typhus, spirochetal jaundice, Leptospirosis, rabies, ratbite fever, and bacterial food poisoning.

Many times rats bite sleeping children while trying to get bits of food on the child that were not washed off before going to bed. Rats and mice also start fires by gnawing matches and electrical wires in homes. The Norway rat, roof rat and house mouse are the most persistent rodent populations in need of control.

Norway Rats

In Florida, 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 harborages 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. 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 harborages in search of water or food.

Color ranges from black to grizzled gray to tan with a light belly. The tail is longer than the combined head and body. Adults weight from ½ to pound. Their droppings are up to 1/2 inch long and spindle-shaped. Roof rats live about 1 year and reach sexual maturity in 3-5 months. They have 6-8 young per litter and up to 6 litters per year.

Behavior

The movement of rats is usually related to food, water, or harborage. Knowing where they are likely to go is important to controlling them. Rats use any method to get to food, water or harborage. Their excellent sense of balance enables them to run on pipes, narrow ledges, and utility wires. Rats, especially roof rats, will climb anything their claws will hold on to, including wires, pipes, and rough walls. Because rats are excellent swimmers, they often live in sewers and occasionally enter homes through toilets.

Rats like to use regular paths or runways along walls or behind debris. To get food in the open, they will run behind things to get as close to the food as possible. They are afraid of strange objects or strange food and may avoid both.

Norway and roof rats are both aggressive species. The Norways are usually more aggressive, driving roofs from the territory. Both species are seldom found in the same building.

Rats frequently gnaw on their surroundings. Their teeth grow 4½ to 5½ inches per year and only gnawing keeps them short and sharp.
Rats are active mostly at night and show greatest activity the first half of the night, if food is abundant. Although they will be active during daytime hours when food is scarce, when there is an overpopulation of rats, or when a poison has been used and the population is sick.

SIGNS OF INFESTATION

Since rats are active at night and are rarely seen during the day, it is necessary to recognize signs of their activity.

Droppings and Urine - Most people first recognize rodent problems by finding droppings or urine stains in and around buildings. Rodents usually have favorite toilet areas but will void almost anywhere. Old droppings are gray, dusty, and will crumble. Fresh droppings are black, shiny, and puttylike. Rodents urinate while running, and the streaks are characteristic. The urine glows under ultraviolet lights and glows blue-white when fresh.

Gnawed Objects - Rodents gnaw every day in order to keep their teeth short and sharp. Rats also gnaw to gain entrance or to obtain food. Teeth marks on food, building materials, wire, and edges of beams are indications of gnawing. They will gnaw holes in wooden walls, pressed wood, and posts. Fresh gnawing in wood is usually light-colored with sharp, splintery edges. Old gnawing is smooth and darker.

Runways - Habitually rodents use the same paths or runways between harborage and food or water. Outside runways are paths 2-3 inches wide and appear as smooth, hardpacked trails under vegetation. Indoors, runways are usually found along walls. Undisturbed cobwebs or dust indicates runways are not being used.

Rubmarks - Along runways, dark greasy rubmarks appear from contact with the rodent's body. Rubmarks on walls appear as black smudges left by the rodent. New rubmarks are soft and will smudge. Old rubmarks are brittle and will flake when scratched. Rafters may show swing marks of roof rats.

Tracks - To detect rodent activity, spread dust material like talcum powder along runways. Footmarks of rats (5-toe hind foot, 4-toe front foot) or tail drag marks will show in the powder.

Burrows - Norway rats burrow for nesting and harborage. Burrows are usually found in earth banks, along walls, under rubbish and concrete slabs. Freshly dug dirt scattered in front of 3-inch openings with runways leading to the openings is characteristic. Burrows usually are 18 inches deep in most soils. Slick, hardpacked runways indicate an old established colony.