of a Rat
C. R. MADSEN
Circular 240 June 1962
AGRICULTURAL EXTENSION SERVICE
University of Florida, Gainesville, Florida
THE TAIL OF A RAT AND MOUSE
C. R. MADSEN
Rodent Control Specialist
Florida Agricultural Extension Service and
Bureau of Sport Fisheries and Wildlife
There are many kinds of rats and mice, but this
tale is about the kinds which live so closely with
people that we call them "domestic rats and
Even among these domestic varieties, there are
differences. Some rats prefer to live in burrows
in the ground and around garbage dumps and hog
pens. These are Norway rats (also called brown
rats, wharf rats, and sewer rats). As a general
rule, rats and mice will eat anything and every-
thing that people eat. But Norway rats are the
ones which thrive in open garbage dumps, and
are usually found around poorly managed hog
yards or rundown waterfronts. They will feed on
meats, fish, and waste scraps much more than
other kinds of rats. In Florida, Norway rats are
most common along the sea coasts. Adults may
weigh from /4 to 1 pound. They often have a
coarse appearance with rounded nose, medium
sized ears, and a tail that is about as long as the
head and body.
Another group of rats common to Florida are
the roof rats (also called climbing rat, fruit rat,
house rat, and Alexanderine rat). Roof rats be-
long to the black rat family, but black color va-
rieties are not very common in Florida. These
rats prefer to live in attics, roof spaces, hollow
walls, and even in palm trees and ornamental
shrubbery. Roof rats are the most common rats
found in the interior of Florida. They are rela-
tively clean feeders. They will eat some table
scraps, but they prefer your kitchen supplies,
cakes and pastries, fruits, nuts, and of course all
kinds of stored livestock feeds and grains. Adults
may weigh from 1/. to %3/ pound. Generally, they
have a trim look, with prominent ears, a some-
what pointed nose, and a tail that is noticeably
longer than the head and body.
House mice sometimes migrate to farm fields
and become relatively numerous, but wild mice
never come into buildings in large numbers. Some
people persist in the belief that house mice grow
up to be full sized rats, but this is not true. House
mice give an appearance of a uniform brownish
color. They have large ears, prominent eyes, and
a tail equal to or longer than the head and body.
They are very quick and nervous.
With sufficient food and living accommoda-
dations, both Norway and roof rats will repro-
duce at a rate that will average about 20 surviv-
ing young per year for each pair of adult rats.
These young mature rapidly and can mate within
3 to 5 months. House mice multiply even faster.
Each pair will average about 30 to 35 survivors
per year, and these young mature to a mating
age in about 40 days.
It is an accepted fact that rats and mice do a
lot of damage, but a great many people are still
not aware of the many ways in which rats cause
damage, or of the overall cost of rats to the
country as a whole. It has been determined that
each rat does about $20 worth of damage per year.
This takes into account the damage to buildings
and property, the waste and contamination of
foods and grains, the fires and damaged motors
caused by short circuits-but it doesn't take into
consideration the spreading of disease, the loss of
sleep caused by prowling rats, or the anguish and
mortification at finding rats taking over homes
and outbuildings. Some of this is a result of peo-
ple not knowing what conditions invite large num-
bers of rats and mice, and not knowing what ac-
tion is required to get rid of them.
House mice usually live their entire lives with-
in an area of 10 or 15 yards, and most of their
damage is in homes, warehouses, livestock feed
rooms, poultry farms, and similar places. Nor-
way and roof rats range over an area of more
than 100 yards and often migrate for miles in
search of a place to live where food, water, and
cover (living spaces) are more suitable. Such new
living places might include warehouses, feed mills,
livestock or hog pens, corn cribs, garbage dumps,
or even your personal garbage can and the attic
of your car-port. It now becomes evident that
the tail of a rat and mouse covers a lot of ground.
It also covers a lot of kitchen tables, cupboard
shelves, barbecue grills, garbage cans, ware-
housed foods, hog pens, poultry yards, livestock
barns, and corn cribs. The list goes on and on
because rats and mice live wherever people live,
and wherever people work.
Rats and mice waste at least 10 times as much
food as they eat, and they contaminate many tons
of additional foods with urine, droppings, and
hair. Several diseases are carried by rats. In
addition to carrying disease, rats damage and de-
stroy property by gnawing. Eat hide gnaw
- scatter filth start fires gnaw eat -
breed hide! That's the life of a rat!
HOW TO GET RID OF YOUR RATS
Many people reverse the steps of rat control.
They become concerned about their rats, so they
clean up the rat living areas and then put out
traps or poison baits. This is the wrong ap-
proach. First put out traps and poisoned baits
and let the rats continue to live how and where
they are used to living. This will make it easier
for you to determine where to put traps and baits.
After the rats have been killed is the time to
clean up the places where they lived and remedy
the conditions which will attract new rats.
Traps.-For homes and places where it is
known that only a few rats are present, traps are
the first choice of control methods. Standard type
wooden snap traps are very suitable. Cage traps
or steel traps can sometimes be used.
Baits for trapping can include rolled oats, cake,
or nut crumbs sprinkled over the trap trigger.
Whole nuts, apple cubes, raisins or dry fruit,
candy, peanut butter, bacon squares, or smoked
fish can be fastened to the trigger. Small wads of
cotton will catch mice.
Wooden traps can be nailed to rafters or under
beams where rats travel. Set traps at right an-
gles to the rat runs so the trigger can be ap-
proached from either side without coming over
the trap. Set along walls, behind furniture, near
stacked feed, and close to holes. For mice it is
necessary to set traps also in desk drawers, on
shelves, and in cupboards where mouse sign has
Poison Baits.-When rats are plentiful, or
where warehouses, outbuildings, or trashy condi-
tions exist, it is usually best to rely on poisoned
There are many ready mixed rat baits available
on the market, and most feed and seed stores,
garden supply stores, or pest control stores handle
such baits. The most successful rat poisons for
public use are those known as anticoagulants.
The most widely known of the anticoagulants
is warfarin, but others which produce equally
good results are Pival, Fumarin, and Diphacin.
Look for one of these names on the packages of
dry cereal bait, or the small packets of water sol-
Anticoagulants require that the rodents feed
from the bait for a period of 7 to 15 days (de-
pending on how quickly they accept the bait).
This makes it necessary to have good clean bait
available during the entire poisoning period, and
the bait must be properly located along rat travel
ways. It should also be protected from contami-
nation by dust, lint, and other dirt. If the rats
can be given a sense of protection and safety, the
speed and success of the control will increase.
About 1 pound of anticoagulant cereal bait
should control the rats in and around most resi-
dential homes. About 4 to 5 pounds of cereal
bait should control the rats on most farms.
(Much less bait is required for mouse control, but
it requires a longer time.) For large farms, feed
mills, or warehouses, more bait will be required.
For these large areas it might be desirable to use
freshly mixed baits. The basic formula of anti-
coagulant cereal bait is 1 part of anticoagulant
0.5 percent concentrate; 1 part sugar; 1 part corn
oil (cooking variety is acceptable); and 17 paits
of cereal such as coarse ground yellow corn meal,
or corn meal and rolled oats mixed.
Place cereal baits in 1/4 to 1/2 pound amounts at
each bait location. The bait should be placed in
shallow containers. (Paper plates can be used.)
Fresh bait should be added each day until control
is accomplished. Use anticoagulant (or unpoi-
soned) water along with cereal baits for added
effect. Water baits can also be used by them-
After rats have been controlled is the time to
clean up all the rat living conditions and to screen
off such places as attic vents, pipe holes, or bro
ken windows where rats have been traveling. Dis
pose of waste livestock feed, bale and store emp
ty burlap bags, and properly stack lumber piles
and surplus equipment. In short-do a good jot
of house cleaning, whether the location is a home
warehouse, barn, or poultry shed. Some of thesis
places will always be an invitation to rats, bu
domestic rats never migrate in large groups. S(
-it is no disgrace to acquire some rats-but it i!
a disgrace to maintain them.
When you control your rats, encourage youi
neighbor to control his rats at the same time
The greater the area that is controlled, the more
effective will be the results and the longer it wil
be until new rats attempt to migrate back to you]
COOPERATIVE EXTENSION WORK IN
AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
Agricultural Extension Service, University of Florida,
Florida State University and
United States Department of Agriculture, Cooperating
M. O. Watkins, Director