|
Rats & mice are some of the
most troublesome and damaging rodents in the
United States.

According to the Texas Cooperative Extension
publication the three primary house infesting
rodents in Texas are the
Norway rat, roof or Alexandrine rat, and the
house mouse. Together they are known as
commensal rodents because they live
in intimate association with man. They consume
and contaminate food, damage structures and
property, and
transmit parasites and diseases to other animals
and humans. Rats live and thrive under a wide
variety of climates and conditions; they are
often found in and around homes and other
buildings, farms, barns, stables, gardens, and
open fields.
People do not often see rats, but signs of their
presence are easy to detect. The most
troublesome rats are
two introduced species: the Roof rat and the
Norway rat.
Norway rats (Rattus norvegicus),
sometimes called brown or sewer rats, are stocky
burrowing rodents that are larger than roof
rats. Their burrows are found along building
foundations, beneath rubbish or woodpiles, and
in moist areas in and around gardens and fields.
Nests may be lined with shredded paper, cloth,
or other fibrous material. When Norway rats
invade buildings, they usually remain in the
basement or ground floor. The Norway rat occurs
throughout the 48 contiguous United States.
Generally it is founds at lower elevations but
may occur wherever people live. Norway rats eat
a wide variety of foods but mostly prefer cereal
grains, meats, fish, nuts, and some fruits. When
searching for food and water, Norway rats
usually travel an area of about 100 to 150 feet
in diameter; seldom do they travel any further
than 300 feet from their burrows or nests. The
average female Norway rat has four to six
litters per year and may successfully wean 20 or
more offspring annually.
Roof rats (Rattus rattus), sometimes
called black rats, and are slightly smaller than
Norway rats. Unlike Norway rats, their tails are
longer than their heads and bodies combined.
Roof rats are very agile climbers and usually
live and nest above ground in shrubs, trees, and
dense vegetation such as ivy. In buildings, they
are most often found in enclosed or elevated
spaces in attics, walls, false ceilings, and
cabinets. The roof rat has a more limited
geographical range than the Norway rat,
preferring ocean-influenced, warmer climates.
|
Roof Rat geographical range |
 |
Roof Rats, Like Norway rats, roof rats eat a
wide variety of foods, but their food
preferences are primarily fruits, nuts, berries,
slugs, and snails. Roof rats are especially fond
of avocados and citrus and often eat fruit that
is still on the tree. When feeding on a mature
orange, they make a small hole through which
they completely remove the contents of the
fruit, leaving only the hollowed out rind
hanging on the tree. The rind of a lemon is
often eaten, leaving the flesh of the sour fruit
still hanging. Their favorite habitats are
attics, trees, and overgrown shrubbery or vines.
Residential or industrial areas with mature
landscaping provide good habitat, as does
riparian vegetation of riverbanks and streams.
Roof rats prefer to nest in locations off the
ground and rarely dig burrows for living
quarters if off-the-ground sites exist.
Roof rats routinely travel up to 300 feet for
food. They may live in the landscaping of one
residence and feed at another. They can often be
seen at night running along overhead utility
lines or fence tops. They have an excellent
sense of balance and use their long tails for
balance while traveling along overhead utility
lines. They move faster than Norway rats and are
very agile climbers, which enables them to
quickly escape predators. They may live in trees
or in attics and climb down to a food source.
The average number of litters a female roof rat
has per year depends on many factors, but
generally is three to five with from five to
eight young in each
litter. In areas
where the roof rat occurs, the Norway rat may
also be present. If you are unsure of the
species, look for rats at night with a strong
flashlight or trap a few. There are several key
physical differences between the two species of
rats; Table 1 summarizes identifying
characteristics.
Table 1. Identifying Characteristics of Adult
Rats
|
Characteristic |
Roof Rat |
Norway Rat |
|
General Appearance |
sleek, agile |
Large, robust |
|
Color of Belly |
gray to white |
mostly grayish |
|
Body Weight |
5 to 10 ounces |
7 to 18 ounces |
|
Tail |
extends at least to snout; black;
fine scales |
short than body; dark above; pale
below; scales |
|
Head |
muzzle pointed |
muzzle blunt |
|
Ears |
long enough to reach eyes if folded
over |
do not reach eyes |
Norway rats do not tolerate large numbers of
each other, but 100 or more roof rats might live
together in an area. Norway and roof rats are
rarely found living in the same building.

Both Norway and roof rats may gain entry to
structures by gnawing, climbing, jumping, or
swimming through sewers and entering through the
toilet or broken drains. While Norway rats are
more powerful swimmers, roof rats are more agile
and are better climbers. Norway and roof rats do
not get along. The Norway rat is larger and the
more dominant species; it will kill a roof rat
in a fight. When the two species occupy the same
building, Norway rats will dominate the basement
and ground floors, with roof rats occupying the
attic or second and third floors. Contrary to
some conceptions, the two species cannot
interbreed. Both species may share some of the
same food resources but do not feed
side-by-side. Rats may grab food and carry it
off to feed elsewhere.
BIOLOGY AND LIFE CYCLE OF THE RAT
Rats, like house mice, are mostly active at
night. They have poor eyesight, but they make up
for this with their keen senses of hearing,
smell, taste, and touch. Rats constantly explore
and learn about their environment, memorizing
the locations of pathways, obstacles, food and
water, shelter, and other elements in their
domain. They quickly detect and tend to avoid
new objects placed into a familiar environment.
Thus, objects such as traps and baits often are
avoided for several days or more following their
initial placement. While both species exhibit
this avoidance of new objects, it is usually
more pronounced in roof rats than in Norway
rats.
DAMAGE CAUSED BY RATS
Rats consume and contaminate foodstuffs and
animal feed. They also damage containers and
packaging materials in which foods and feed are
stored. Both species of rats cause problems by
gnawing on electrical wires and wooden
structures (doors, ledges, in corners, and in
wall material) and tearing up insulation in
walls and ceilings for nesting.
Norway rats may undermine building foundations
and slabs with their burrowing activities. They
may also gnaw on all types of materials,
including soft metals such as copper and lead as
well as plastic and wood. If roof rats are
living in the attic of a residence, they can
cause considerable damage with their gnawing and
nest-building activities. They also damage
garden crops and ornamental plantings.
Among the diseases rats may transmit to
humans or livestock are murine typhus,
leptospirosis, trichinosis, salmonellas (food
poisoning), and rat bite fever. Plague is a
disease that can be carried by both roof and
Norway rats, but in California it is more
commonly associated with ground squirrels,
chipmunks, and native wood rats.
Rats of either species,
especially young rats, can squeeze beneath a
door with only a 1/2-inch gap. If the door is
made of wood, the rat may gnaw to enlarge the
gap, but this may not be necessary.
How to Spot a Rat Infestation
Because rats are active throughout the year,
periodically check for signs of their presence.
Once rats have invaded your garden or
landscaping, unless your house is truly rodent
proof, it is only a matter of time before you
find evidence of them indoors. Experience has
shown it is less time consuming to control
rodents before their numbers get too high, and
fewer traps and less bait will be required if
control is started early.
Inspect your yard and home
thoroughly. If the answer to any of the
following questions is yes, you may have a rat
problem.
-
Do you find rat droppings
around dog or cat dishes or pet food storage
containers?
-
Do you hear noises coming
from the attic just after dusk?
-
Have you found remnants of
rat nests when dismantling your firewood
stack?
-
Does your dog or cat bring
home dead rat carcasses?
-
Is there evidence rodents
are feeding on fruit/nuts that are in or
falling from the trees in your yard?
-
Do you see burrows among
plants or damaged vegetables when working in
the garden?
-
Do you see rats traveling
along utility lines or on the tops of fences
at dusk or soon after?
-
Have you found rat nests
behind boxes or in drawers in the garage?
-
Are there smudge marks
caused by the rats rubbing their fur against
beams, rafters, pipes, and walls?
-
Do you see burrows beneath
your compost pile or beneath the garbage
can?
-
Are there rat or mouse
droppings in your recycle bins?
-
Have you ever had to remove
a drowned rat from your swimming pool or hot
tub?
-
Do you see evidence of
something digging under your garden tool
shed or doghouse?
While rats are much larger than
the common house mouse or meadow vole, a young
rat is occasionally confused with a mouse.
In
general, very young rats have large feet and
large heads in proportion to their bodies,
whereas those of adult mice are much smaller in
proportion to their body size. While both rats
and mice gnaw on wood, rats leave much larger
tooth marks than those of a mouse.

Mice make smaller, neater nests that are
normally placed inside any kind of shelter
ranging from underneath paper sacks to loose
hay, or even inside upholstered furniture
Because rats (and house mice) are excellent
climbers, openings above ground level must also
be plugged.
Signs of mouse infestation include visible
droppings, tracks seen in moist or dusty areas,
burrows in the ground or in hay stacks and
nests. Gnawing signs and greasy looking smears
that are left when their bodies touch walls or
rafters may also be seen. In poorly ventilated
areas you might even be able to smell them.
Quietly listening for running and
squeaking/squealing sounds after dark in areas
where infestation is suspected might help
confirm their presence as well.
Principle methods for controlling mice include
removing shelter - prompt disposal of empty feed
sacks and boxes, and storing lumber and other
materials at least 18 inches off the ground with
a space between the material and the wall.
MANAGING A RAT or MICE
PROBLEM
Three elements are necessary for a successful
rat management program: sanitation measures,
building construction and rodent proofing, and,
if necessary, population control.
-
Sanitation
Sanitation is fundamental to rat control and
must be continuous. If sanitation measures
are not properly maintained, the benefits of
other measures will be lost, and rats will
quickly return. Good housekeeping in and
around buildings will reduce available
shelter and food sources for Norway and, to
some extent, roof rats. Neat, off-the-ground
storage of pipes, lumber, firewood, crates,
boxes, gardening equipment, and other
household goods will help reduce the
suitability of the area for rats and will
also make their detection easier. Garbage,
trash, and garden debris should be collected
frequently, and all garbage receptacles
should have tight-fitting covers. Where dogs
are kept and fed outdoors, rats may become a
problem if there is a ready supply of dog
food. Feed your pet only the amount of food
it will eat at a feeding, and store pet food
in rodent-proof containers.
-
Building Construction and
Rodent Proofing
The most successful and long lasting form of
rat control in buildings is to "build them
out." Seal cracks and openings in building
foundations, and any openings for water
pipes, electric wires, sewer pipes, drain
spouts, and vents. No hole larger than 1/4
inch should be left unsealed to exclude both
rats and house mice. Make sure doors,
windows, and screens fit tightly. Their
edges can be covered with sheet metal if
gnawing is a problem. Coarse steel wool,
wire screen, and lightweight sheet metal are
excellent materials for plugging gaps and
holes. Plastic sheeting, wood, caulking, and
other less sturdy materials are likely to be
gnawed away.
Population Control
When food, water, and shelter are available, rat
populations can reproduce and grow quickly.
While the most permanent form of control is to
limit food, water, shelter, and access to
buildings, direct population control is often
necessary
Steps To Rid Property of Rodents
Rats and mice around the home or farm are no
laughing matter. Aside from causing damage to
feedstuffs, rats and mice can be vectors of
disease.
If you discover that you
have rats or mice living in or around your
residence.
Please call BugFree Termite & Pest for your
rodent control services.
We care about you and want to keep you safe.
***The Texas Department of
State Health Services has recommended these
precautions for dealing with
rats and mice after two people in the state
developed Hantavirus pulmonary syndrome this
year***
-
Wear protective gloves when
handling dead mice and rats or when cleaning
up nesting areas, urine or droppings.
-
Open windows and ventilate
the inside area for at least 30 minutes
prior to cleaning up nests or droppings.
-
Do not stir up nests by
sweeping or vacuuming. Dampen areas before
cleanup.
-
Use a disinfectant or make a
1-part-to-10-part bleach-water mixture to
clean up dead rodents, nests, urine or
droppings.
By calling
BugFree Termite and Pest
you can be assured of a professional
recommendation and program
for dealing with any animal or rodent problem.
SCHEDULE A FREE INSPECTION
TODAY
|