all possible entrances. Poorly fitting doors
and improper masonry around external
pipes can be flashed or covered with metal or
filled with concrete to block entry of rodents.
Vents, drains, and windows should be cov-
ered with screens. Because decay in building
foundations will permit rats to burrow into
buildings, masonry should be repaired, and
fan openings and other potential entrances
should be blocked.
Rodent control is enhanced through
depriving them of a location to reside
(harborage). Shapton and Shapton (1991)
have suggested that outside equipment must
be raised 23 to 30 cm clear of the surface to
prevent rodent harborage. Shrubbery should
be at least 10 m away from food facilities.
Katsuyama and Strachan (1980) recommend
that a grass-free strip 0.6 to 0.9 m in size be
covered with a layer of gravel or stones 2.5 to
3.8 cm deep around food-processing build-
ings. This feature helps to control weeds and
rodents, and is convenient for the sanitation
inspection rodent bait stations or traps
placed against the building. Shapton and
Shapton (1991) suggested that employees
not eat on the plant grounds because
dropped food attracts rodents, birds, and
insects.
Elimination of Rodent Shelters
Crowded storage rooms with poor house-
keeping provide sheltered areas for rodents
to build nests and reproduce. Rodents thrive
in areas where garbage and other refuse are
placed. These sheltered areas are less attrac-
tive to rodents if garbage is stored 0.5 m
above the floor or ground. If waste contain-
ers are stored on concrete blocks, hiding
places beneath them are eliminated. Waste
containers should be constructed of heavy-
duty plastic or galvanized metal with tight-
fitting lids. Housekeeping can be improved,
with concomitant protection against rodent
infestation, by storing foodstuffs on racks at
least 15 cm above the floor or away from the
walls. A white strip painted around the edge
of the floor of storage areas reminds work-
ers to stack products away from the walls
and aids in the identification of rodent infes-
tation through the presence of tracks, drop-
pings, and hair.Elimination of Rodent Food Sources
Proper storage of food and supplies com-
bined with effective cleaning can aid in the
elimination of food sources for rodents.
Prompt cleaning of spills, regular sweeping
of floors, and frequent removal of waste
materials from the premises also reduce
available food for rodents. Food ingredients
and supplies should be stored in properly
constructed containers that are tightly
sealed.Eradication
The more effective methods of eradicating
rodents are poisoning, gassing, trapping, and
ultrasonic devices.Poisoning
Poisoning is an effective method of eradi-
cation; however, precautions are necessary
because poison baits are hazardous if con-
sumed by humans. Examples of rodenticides
are the anticoagulants, such as 3-(αacetonyl-
furfuryl)-4-hydroxycoumarin (fumarin), 3-(α
acetonylbenzyl)-4-hydroxycoumarin (war-
farin), 2-pivaloyl-1,3-indandione (pival),
brodifacoum, bromodiolone, and chloropha-
cinone. These multi-dose poisons must be
consumed several times before death occurs
and accidental consumption of poisoned bait
does cause danger.
The multiple-dose anticoagulants (chronic
poisons), although safer than most other
poisons, should be prepared and applied
according to directions. The ideal locations
for application are along rodent runways and
near feeding sites. Fresh bait should be putPest Control 247