varieties, are almost as cunning as rats. They
are known to enter a building through a hole
as small as a nickel. They are skilled swim-
mers that can swim through floor drains and
toilet bowl traps; and they have an excellent
sense of balance. Like rats, mice are filthy
rodents and can spread diseases similar to
those spread by rats. The house mouse,
which is found everywhere in the United
States, has a body length of 6 to 9 cm and
weighs approximately 14 to 21 g. It has a
small head and feet and large prominent
ears.
Mice attain sexual maturity in approxi-
mately 1.5 months. Female mice produce
5 to 6 offspring per litter, up to 8 times per
year. The typical female weans 30 to 35 young
per year. Mice do not need a source of water
because they can survive on water that they
metabolize from food sources. However, they
will drink liquids if available.
Mice are easily carried into food premises
in crates and cartons. They are easier to trap
than rats because they are less wary. Metal
and wood-base snap traps are normally
effective. Several traps may be spaced about
1 m apart. Hill (1990) stated that mice usu-
ally accept a new object, such as a trap, often
after about 10 minutes. Sodium fluorosilicate
and the anticoagulant chlorophacinone are
poisonous tracking powders that are effec-
tive in mice control. Except for red squill,
mice are destroyed with the same poisons
as rats.
Determination of Infestation
Rats and mice are nocturnal animals.
Because they tend to be inactive during day-
light hours, their presence is not always
immediately detected. The presence of fecal
droppings is one of the obvious signs of
rodent infestation. Rat droppings range from
13 to 19 mm in length and up to 6 mm in
diameter. Fecal material from the house
mouse is approximately 3 mm long and
1 mm in diameter. Fresh droppings are black
and shiny, with a pasty consistency. Older
fecal material is brown and falls apart when
touched.
Rats and mice generally follow the same
path or runway between their nests and
sources of food. In time, grease and dirt
from their bodies form visible streaks on
floors and other surfaces. Because rodents
tend to keep in contact with vertical surfaces
when they travel, runways along walls,
rafters, steps, and inner sides of pipes are fre-
quently visible. Rat and mouse tracks can be
seen on dusty surfaces with light shining
from an acute angle. Rodent tracks are iden-
tified through spreading talc in areas with
suspected rodent activity. Urine stains may
be detected through the use of long-wave-
length UV light, which will cause a yellow
fluorescence on burlap bags and a pale, blue-
white fluorescence on kraft paper.
The incisor teeth of rats are strong enough
to gnaw through metal pipes, unhardened
concrete, sacks, wood, and corrugated mate-
rials to reach food. Teeth marks can be
observed if gnawings are recent. A bumping
noise at night, accompanied by shrill
squeaks, fight noises, or gnawing sounds are
clues that rodents may be present.Control
Control of rodents, especially rats, is diffi-
cult because of their ability to adapt to the
environment. The most effective method of
rodent control is proper sanitation. Without
an entrance to shelter and the presence of
debris, which can nourish rodents, these pests
cannot survive and will migrate to other loca-
tions. Without effective sanitation practices,
poisons and traps will provide only a tempo-
rary reduction in a rodent population.Prevention of Entry
Protection against rats is accomplished
most effectively through the elimination of