MANAGEMENT PIH-107
PURDUE UNIVERSITY. COOPERATIVE EXTENSION SERVICE.
WEST LAFAYETTE, INDIANA
Controlling Rats and Mice in Swine Facilities
Authors:
Robert M. Timm, University of Nebraska
Rex E. Marsh, University of California
Robert M. Corrigan, Purdue University
Ken Holscher, Iowa State University
Reviewers:
Bob and Diane Bell, Camden, Arkansas
Peter T. Bromley, Virginia Polytechnic Institute and State University
William Fitzwater, Albuquerque, New Mexico
Mike and Debbie Nichols, Oakfield, Tennessee
Rats and mice can be a major economic threat around swine
facilities. They consume and contaminate feed and cause feed
losses through the gnawing of holes in feed sacks and wooden
bins. They may also be responsible for maintaining or spreading
swine diseases.
House mice (Mus musculus), Norway rats (Rattus norvegicus),
and roof rats (Rattus rattus) as a group are considered the most
troublesome and economically important rodents in the United
States. These non-native ``commensal'' rodents live under a
variety of urban and rural conditions. They may thrive in and
around farms and rural homes and in some situations inhabit open
fields and agricultural crops.
Norway rats will undermine building foundations and concrete
slabs. Roof rats and house mice, in addition to Norway rats, are
particularly destructive to building insulation. Most common
types of insulation including rigid foam and fiberglass are sus-
ceptible to rodent damage. A rodent infestation can damage struc-
tures by thousands of dollars in a matter of months. Addition-
ally, rodents may gnaw on electrical wiring causing equipment
malfunction, power outages, and potentially dangerous short cir-
cuits.
Norway rats and house mice are found in all of the contigu-
ous 48 states, although the Norway rat may be absent from some
relatively large geographic areas of the West. The roof rat pri-
marily occupies the coastal areas of Washington, Oregon, and Cal-
ifornia, as well as a larger area along the Gulf and Atlantic
coast states from Texas to Maryland. In general, the roof rat is
considerably less important to the pork producer.
Rodents and Swine Diseases
Rodents and other wildlife can be significant in the
transmission of swine diseases. The actual occurrence of such
diseases in rodents, and the degree to which they contribute to
disease problems on hog farms, is poorly documented.
Table 1 lists swine diseases that rats and mice may harbor
or disseminate. Rodents, like other wild animals, insects, and
people, are capable of carrying diseases directly into a swine
facility upon their entry. Rodents can spread or accelerate the
spread of established diseases from contaminated areas to uncon-
taminated areas via their droppings, feet, fur, urine, saliva, or
blood. As an example, Norway rats may travel through infected
feces of isolated sick pigs and then contaminate the food and
water of healthy animals some several hundred feet away.
Additionally, rodents around farm buildings are a food
source that may attract wild predatory animals such as foxes,
coyotes, raccoons, and skunks, which in turn may contribute to
disease problems. Rodents may also attract stray dogs and cats
which can transmit still other diseases. An effective disease
barrier system cannot be achieved or maintained without good
____________________________________________________________________
|Table 1. Diseases of swine in North America that rodents may har- |
|bor or disseminate. |
| |
|_________________________________________________________________ |
| Rodents |
|Disease Agent implicated |
|_________________________________________________________________ |
|Bordetellosis bacteria rats |
|Encephalomyocarditis virus rats, mice |
|Leptospirosis bacteria rats, mice |
|Pseudorabies virus rats* |
|Salmonellosis bacteria rats, mice |
|Swine dysentery bacteria rats, mice |
|Swine erysipelas bacteria rats |
|Toxoplasmosis protozoan various rodents |
|Trichinosis nematode rats |
|_________________________________________________________________ |
| |
|* Opinions differ on the significance of rodents as the reservoir |
|__________________________________________________________________|
Recognizing Rodent Infestation
Droppings, tracks, burrows, pathways, and fresh gnawings,
including rodent-damaged feed sacks, indicate areas where rodents
are active. Rodent nests, made from fine shredded paper or other
fibrous material, are often found in sheltered locations. Around
swine facilities, insulated walls and ceilings are common nesting
locations for rodents, especially mice. Rats utilize these areas
and also burrow into the ground inside and outside of swine
buildings. When present in relatively high numbers, these
rodents occasionally can be seen during daylight hours, but they
are most active at night, particularly just after dusk. Thus,
conducting an inspection of the premises at nightfall may assist
in identifying the location, distribution, and severity of a
rodent infestation.
Rat and Mouse Facts
House mice are nondescript, brownish to greyish rodents with
relatively large ears and small eyes. They weigh about 1/2 oz. An
adult is about 51/2-71/2 in. long including the 3- to 4-in. tail.
Norway rats are large, robust animals whose fur color ranges from
reddish to greyish brown on the back and sides and grey to
yellow-white underneath. They are about 13-18 in. long including
the 6- to 81/2-in. tail. Average weight is about 11 oz., and few
individuals exceed 1 lb. In comparison, the roof rat is a
smaller, sleeker rat usually colored blackish to grey, with a
grey to whitish underside. A roof rat, in contrast to the Norway
rat, has a tail longer than its body and a more pointed snout.
Also, its eyes and ears are relatively larger than the Norway's.
Although commensal rodents often feed on cereal grains, they
will eat many kinds of food including garbage, insects, meat, and
even manure. House mice are sporadic feeders, nibbling bits of
food here and there, but often causing more economic loss from
gnawed feed sacks, contaminated feed, or from transmitted disease
than from actual food consumed. Rats tend to get their daily food
at one or two locations. Rats require 1/2-1 fl. oz. of water
daily (unless feeding on moist or succulent foods), but house
mice can survive for long periods without liquid.
Rats and mice have keen senses of taste, hearing, smell and
touch. Roof rats, in particular, are excellent climbers and often
live on the second story of two-story farm buildings if food is
available. House mice and Norway rats will climb to reach food or
shelter, and all three rodent species can climb any rough verti-
cal surface. They can run horizontally along wire cables or ropes
and can jump up 36 in. (12 in. for house mice) from the floor
onto a flat surface.
These rodents have impressive capacities for reproduction,
which makes it necessary to control them diligently and early,
before they reach populations that cause significant damage. For
example, in a single year a female house mouse may have 5-10
litters of usually 5 or 6 young each. Young are born 19-21 days
after mating, and they reach reproductive maturity in 6-10 weeks.
The life span of a mouse is usually 9-12 months. Norway and roof
rats are only slightly less fecund, with individuals typically
living 9-12 months but sometimes longer. Where both rats and
house mice exist on the same premises, rats may exclude house
mice from their main areas of activity. Following the control of
rats, mice may flourish.
Rodent Control
Effective control involves (1) sanitation, (2) rodent-proof
construction, and (3) population reduction. The first two are
useful as preventive measures. When a rodent infestation already
exists, population reduction is almost always necessary. Reduc-
tion techniques include trapping, poisoning, and fumigation.
Sanitation. Although good sanitation will seldom eliminate
rodents, it will certainly aid in controlling them. Conversely,
poor sanitation is sure to attract rodents and permit them to
thrive in greater abundance. The continual presence of a sizable
rodent population suggests that too little attention is given to
the premises; often this goes hand-in-hand with poor sanitation.
Inadequate sanitation contributes to more serious rodent prob-
lems, but rodent infestation (particularly house mice) does not
necessarily mean that sanitation is inadequate.
On farms where feed grains are handled and stored, or where
livestock are housed and fed, it is generally impossible to
exclude rodents from all available food. In such situations,
removing shelter that rodents can use for hiding, resting and
nesting is valuable in control. Regular removal of debris and
control of weeds around structures will reduce the amount of
shelter available to rodents. Additionally, a clean, 3-foot
weed-free perimeter around structures may make rodents feel more
``exposed'' and permits easier detection of rodent activity.
Because mice can survive in very small areas with limited
food and shelter, it is almost impossible to eliminate them
through sanitation alone, particularly on farms. Most buildings
in which livestock feed is stored, handled, or used will support
a thriving population of house mice if not mouse-proof. Store
feeds in rodent-proof buildings, rooms, or containers whenever
possible. Bins used for bulk feed should be kept rodent-proof.
Stack sacked feed on pallets with adequate space left around and
under stored articles to allow easy inspection for rodent sign
and placement of traps or baits.
Rodent-proof Construction. A lasting form of rodent control
is to ``build them out'' by eliminating all openings through
which they can enter a structure. Rodent-proof all places where
feed is stored, processed, or used, if feasible.
The paired front (incisor) teeth of rats and mice curve
slightly inward. This makes it difficult for them to gnaw into a
flat, hard surface. However, when given a rough surface or an
edge to bite into, they can quickly gnaw into most materials. By
gnawing, rats can gain entry through any opening greater than 1/2
in. across. Mice can enter a building through any opening larger
than 1/4 in. across. To prevent rodent entry, seal all such holes
with durable materials. Steel wool, packed tightly into openings,
is a good temporary plug. To close openings or protect other
areas subject to gnawing, use materials such as those listed in
Table 2. Plastic sheeting or screen, wood, rubber, or other gnaw-
able materials are not adequate for sealing openings used by
rodents. Close openings around augers, pipes and wires where
they enter structures with portland cement mortar, masonry or
metal collars. Even a small unprotected opening can be an invita-
tion to rodents. A common entry point for mice into buildings is
the unprotected end of metal siding. If not blocked with metal or
mortar, these openings provide access into wall spaces and the
building interior. Rubber or vinyl weather stops are quickly
gnawed through. Design or modify buildings using metal siding so
these openings are not present.
Doors, windows, and screens should fit tightly. It might be
necessary to cover the edges with metal to prevent gnawing.
Depending on the age and type of building construction, it might
not pay to make the infested building rodent-proof. In such
instances, give more attention to other techniques of rodent con-
trol.
Rats can be discouraged from burrowing near building founda-
tions by installing a strip of heavy gravel around their perime-
ter. Gravel should be at least 1 in. in diameter and laid in a
band at least 2 ft. wide and 6 in. deep. Table 2. Recommended
materials for rodent proofing.
________________________________________________________________________________
Material Thickness Remarks
________________________________________________________________________________
Concrete Minimum 2 in. If reinforced.
Minimum 33/4 in. If not reinforced.
Galvanized sheet metal 24 gauge or heavier Perforated sheet metal
grills should be 14 gauge.
Brick 33/4 in. With joints filled with mortar.
Hardware cloth (wire mesh)19 gauge 1/2 x 1/2 in. To exclude rats.
24 gauge 1/4 x 1/4 in. To exclude mice.
Aluminum 22 gauge For frames and flashing.
20 gauge For kick plates.
18 gauge For guards.
________________________________________________________________________________
Trapping. Trapping is an effective way to control rodents.
House mice are relatively easy to trap, but trapping rats
requires more skill and labor. Trapping is the method to try
first where rodents are few, but it may be too time-consuming in
severe infestations. Trapping has several advantages: (1) it
does not rely on potentially hazardous rodenticides; (2) it per-
mits the user to view his success; and (3) it allows for disposal
of the rodent carcasses, thereby eliminating dead animal odors,
which may occur when poisoning is done within buildings.
The simple, inexpensive wood-based snap trap is effective.
Recently new and improved snap traps for rats and mice have
become available. These traps, made of sturdy plastic or metal,
are easier to set and effective when used correctly. Snap traps
are available through farm supply or hardware stores and from
pest control suppliers. Bait the traps with a mixture of peanut
butter and rolled oats or with a small piece of bacon tied
securely to the trigger. Set them so that the trigger is sensi-
tive and will spring easily. Leaving traps baited but unset until
the bait has been taken at least once reduces the chance of
creating trap-shy rodents. Multiple-capture live traps for mice,
such as the Victor Tin CatO and the Ketch-AllO are effective and
will save service time. They, too, are available in some hardware
and feed stores as well as from pest control suppliers.
Set traps close to walls, behind objects, in dark corners
and in places where rodent activity is evident. Tracking patches
of flour or fine sand can be used to determine where rodents are
active. Traps may be placed on ledges or on top of pallets of
stored materials if mice or rats are active there. Where possi-
ble, place snap traps so that rodents will pass directly over the
trigger as they follow their natural course of travel, usually
close to a wall (Figure 1). Newer snap traps have enlarged
triggers, but bait pans on older traps can be easily enlarged so
that rodents are more likely to trigger the trap when traveling
over it. When set correctly, it is possible to catch rodents that
are not even attracted to the bait.
Use enough traps to make the campaign short and decisive.
Mice, in particular, seldom venture far from their shelter and
food supply, so space snap traps no more than 10 feet apart in
areas where mice are active. When using snap traps, it may be
best to trap intensively for 2 or 3 weeks and then ``rest'' for a
couple weeks before resuming efforts. This may save some labor
costs and helps prevent rodents from becoming ``trap-shy.'' Place
multiple catch traps in areas where mice seem especially per-
sistent and in areas of the building where mice may be gaining
regular access (for example, on both sides of doorways).
An alternative to traps are glue boards, which catch and
hold rodents attempting to cross them in much the same way flypa-
per catches flies. Place glue boards along walls where rodents
travel. Because they stick tenaciously to any object coming in
contact with them, do not use them where children, pets or desir-
able wildlife have access to them. Glue boards lose their effec-
tiveness in dusty areas unless covered, and extremes of tempera-
ture also may affect their tackiness. The glue board can be
placed inside a suitable cardboard box with appropriate holes cut
for the rodents to enter. This also aides in disposal of car-
casses. Glue boards are generally more effective for capturing
mice than rats.
Using Poison Baits (Rodenticides). Both anticoagulant and
non-anticoagulant rodenticides (rodent poisons) are available.
Although ready-to-use baits come in a wide variety of types, some
persons highly knowledgeable in rodent control prefer to mix
their own baits using rodenticide concentrates. In most situa-
tions, ready-to-use commercial baits are preferred because they
have proven efficacy and do not require that the applicator han-
dle the concentrated toxicant, which is more hazardous.
Table 3. Non-anticoagulant rodenticides and some of their useful
characteristics for controlling rats and mice in swine facilities.
____________________________________________________________________________
Percent
a.i.* in
food Mode of Time to
Common name Chemical name bait action death
____________________________________________________________________________
bromethalin N-methyl-2,4-dinitro- 0.01 CNS depression 2-4 days
(AssaultO N-(2,4,6-tribromophenyl)- and paralysis
VengeanceO) 6-trifluoromethyl)
benzenamine
cholecalciferol9,10-Seocholesta-5,7, 0.075 Mobilizes cal- 3-4 days
(QuintoxO 10(19)-trein-3-betaol cium resulting
RampageO) in death from
hypercalcemia
red squill scilliroside 10.0 Heart paralysis < 24 hrs.
glycoside**
strychnine strychnine 0.25-1 Tetanic convul- 1/4-3 hrs.
sions leading
to respiratory
failure
zinc phosphide zinc phosphide 1.0-2 Phosphine gas 1/2-20 hrs.
enters circu-
latory system;
heart paralysis,
gastrointestinal,
and liver damage
____________________________________________________________________________
Table 3. (Continue..)
______________________________________________________________
Rodents controlled
__________________
Bait ac-Bait Human Swine House Norway Roof
Common name ceptanceshyness hazardhazard mice rats rats
______________________________________________________________
bromethalin good none mod unk yes yes yes
(AssaultO reported
VengeanceO)
cholecalciferol fair- none low- unk yes yes yes
(QuintoxO good reported mod
RampageO)
red squill poor- mod- low low no yes no
fair high
strychnine fair mod- mod- mod yes no no
high high
zinc phosphide fair mod- mod mod yes yes yes
high
______________________________________________________________
* Active ingredient.
** Principal active ingredient.
NOTE: Rodenticides such as ANTU, arsenic trioxide, and phosphorus
are registered and available in some states, although they are
rarely used today because of their limited availability and low
efficacy in most situations. Both arsenic and phosphorus are quite
toxic to swine and in some countries have been used to control
feral pigs.
Some non-anticoagulant rodenticides (Table 3) will give a
quicker knockdown of a rodent population than anticoagulants, as
they are effective with a single feeding and are relatively rapid
in action. They may be preferred where rodents are abundant or
where it is difficult to get them to accept a bait for several
days in succession (as may be necessary with some anticoagulants)
because of competing food items.
With most non-anticoagulant rodenticides, ``prebaiting''
with poison-free bait for several days before the rodenticide is
offered will increase bait acceptance, thereby increasing control
success. Because ``bait shyness'' or ``poison shyness'' may
develop following a sublethal ingestion of some single-dose
rodenticides such as zinc phosphide or red squill, it is best not
to use these more than twice a year at a given location, and
preferably only once. Because non-anticoagulant rodenticides are
generally more rapid in action and because first aid and anti-
dotes are often less effective, some of these materials are more
hazardous to humans, pets, or livestock if accidentally ingested.
Table 4. Anticoagulant rodenticides for controlling rats and mice
in swine facilities. All anticoagulants have the same mode of
action and all have a delayed time to death, although some act
slightly faster than others. All anticoagulants are effective
against house mice, Norway rats, and roof rats. They all are con-
sidered to have good bait acceptance, no bait shyness, low human
hazard, and moderate-to-high hazard to swine.
___________________________________________________________________
Percent
a.i.* in
food
Common name Chemical name bait
___________________________________________________________________
brodifacoum** 3-{3-[4'-bromo(1,1'-biphenyl)- 0.005
(HavocO 4-yl]-1,2,3,4-tetrahydro-1-
TalonO) naphthalenyl}-4-hydroxy-2H-1-
benzopyran-2-one
bromadiolone** 3-{3-[4'-bromo(1,1'-biphenyl)- 0.005
(MakiO 4-y1]-3-hydroxy-1-phenylpropyl}-
ContracO) 4-hydroxy-2H-1-benzopyran-2-one
chlorophacinone 2-{(p-chlorophenyl) penylacetyl}- 0.005
(RoZolO) 1,3-indandione
diphacinone 2-diphenylacetyl-1,3-indandione 0.005
(RamikO)
coumafuryl 3-(a-acetonylfurfuryl)-4- 0.025
(FumarinO) hydroxycoumarin
pindone
(PivalO) 2-pivalyl-1,3-indandione 0.025
ValoneO 2-isovaleryl-1,3-indandione 0.055
ProlinO 3-(a-acetonylbenzyl)-4-hydroxycoumarin 0.025
+ sulfaquinoxaline (0.025%)
warfarin 3-(a-acetonylbenzyl)-4-hydroxycoumarin 0.025
___________________________________________________________________
* Active ingredient.
** Effective on anticoagulant (warfarin)-resistant rats and mice.
Anticoagulant rodenticides (Table 4) cause death by internal
bleeding, which occurs as the animal's blood loses its clotting
ability and capillaries are destroyed. The active ingredients are
used at very low levels, and bait shyness does not occur pri-
marily because of their slow action.
Most anticoagulant baits cause death only after they are
eaten for several days. Brodifacoum and bromadiolone baits are
exceptions, as these rodenticides can cause death following a
single feeding, although the rodent may continue to feed for
several days. All anticoagulant rodenticides are relatively
slow-acting, and death usually occurs 3 to 5 days following the
ingestion of a lethal amount.
When multiple-dose anticoagulant rodenticides are used, bait
must be available continuously until all rodents stop feeding.
This usually takes at least two weeks. Complete elimination of
rodents is often possible with anticoagulant rodenticides. This
is more rarely the case with non-anticoagulant rodenticides and
hence the anticoagulants are often used as a followup to other
types of control.
Occasionally populations of rodents develop which are resis-
tant to the multiple-dose anticoagulants. This usually occurs
following long, continual use of these products. Such rodents can
be controlled by using the single-dose anticoagulants brodifacoum
or bromadiolone or by using one of the non-anticoagulants.
Bait Selection and Placement. Rodent baits are available in
several forms. Grain baits in a loose meal or pelleted form are
available in small plastic, cellophane, or paper packets. These
sealed ``place packs'' keep bait fresh and permit easy placement
of the baits into burrows, walls, or other locations. Rodents
gnaw into the packet to feed on the bait.
Anticoagulant baits formulated into paraffin blocks are use-
ful in damp locations where loose grain baits would spoil
quickly. Take care to avoid placing them in locations where they
could be reached and fed on by pigs.
A particularly good bait material for house mice is canar-
ygrass seed. In many situations, mice prefer such bait to hog
feed or other cereal grains. Where ample feed is available to
rodents, control can be improved by using baits prepared of
highly-preferred foods. Likewise, those anticoagulant baits,
which are lethal in a single feeding, are more effective in these
situations.
Where water is scarce or absent, water or food items of high
water content are often preferred to dry baits. Some anticoagu-
lant rodenticide concentrates are available to be dissolved in
water to make a liquid bait. Even though mice require little
water to survive, they will quickly accept available water baits.
When the water sources of rats can be reduced or eliminated,
liquid baits will provide excellent control. Liquid baits can
also supplement cereal baits, resulting in better control.
Important! Proper placement of baits and the distance
between placements is important for successful control. Baits or
traps must be located where rodents are living. Place baits or
traps as close to their shelter as the rodent's alternative food
resources. For house mice, space bait placements no farther than
10 ft. apart (preferably 6-8 ft.) in areas where mice are
present. Since rats will travel farther to feed, baits can be
spaced 25-50 ft. apart. But whenever possible, place rat baits
directly into, or very close to, rat burrows.
Bait boxes or stations provide a secluded feeding area,
holding ample multiple-dose, anticoagulant bait for the rodents
in that area. Bait boxes protect the bait from weather and
exclude pets and other nontarget animals. Bait stations should
be large enough to accommodate several rodents at one time and
should have at least two rodent-size openings (11/2 in. for mice;
21/2 in. for rats). Place bait boxes next to walls (with the
openings close to the wall), or near burrows and in other places
where rodents are active. Clearly label all bait boxes with
``Rodent Bait Do Not Touch'' or other appropriate warnings as a
safety precaution. To prevent bait boxes from being tipped over,
fasten them to the floor or wall (Figure 2). Where young chil-
dren, pets, or livestock may be present, secure the lids to
prevent unwanted access to the bait. Two designs for homemade
bait stations are shown in Figure 3. Some of the newer,
``tamper-proof'' bait stations available from pest control supply
distributors are more durable and will hold up inside swine
structures better than light plastic or cardboard stations.
Fumigants. Fumigants are commonly used to control Norway
rats in their burrows in outdoor situations. Compounds such as
carbon monoxide (gas cartridges) and aluminum phosphide have been
used to fumigate rat burrows. Fumigation of house mice is usu-
ally limited to situations where they occur inside structures
such as grain bins or warehouses. Caution! Fumigants are highly
toxic to people and animals, and must not be used in any situa-
tion that might expose people or domestic animals to the gases.
Because of inherent potential hazards with fumigants such as
chloropicrin and methyl bromide, only licensed structural pest
control operators should use fumigants in any situation involving
buildings or other structural enclosures.
Maintaining Control. Once ``control'' is achieved, some pork
producers tend to let their guard down and not pay much attention
to rodent control for a couple of months. Unfortunately, this
habit leads to ``undoing'' all the work it took to control the
rodents initially. Keep in mind that a few rodents are likely to
survive even the most thorough control effort. And, rodents from
nearby fields or structures may invade swine facilities at any
time. These rodents will multiply quickly if not kept in check
with an ongoing control program. Therefore, it is important to
establish permanent bait stations in buildings and around their
perimeters. Fresh anticoagulant bait in these stations will con-
trol invading rodents before breeding populations become esta-
blished.
Rodent control should be a regular and continual part of a
pork production operation. Make it a point to put aside an hour
or two each month after control has been achieved to check and
refill bait stations and inspect facilities for fresh rodent
signs. Mark it on the calendar.
Safety Precautions. Certain general safety precautions
should be followed in addition to those appearing on the labels
of products. Consider all rodenticides dangerous enough to cause
death to pigs, and place baits where only rodents can get to
them. All known rodenticides present some degree of hazard to
animals besides rodents. The anticoagulants and some non-
anticoagulant rodenticides may present some hazard to predators
or scavengers which feed on the carcasses of poisoned rodents.
Therefore, take care to keep baits out of the reach of domestic
animals or nontarget wildlife. Remember that hogs will often feed
on rodent carcasses. Handle rodent carcasses with rubber gloves,
long tongs, or newspaper, and bury or incinerate all dead
rodents. As an added safety precaution, keep dogs or cats con-
fined or well-fed while baiting operations are in progress.
Label all bait containers and stations clearly with
appropriate warnings, and keep unused bait in its original con-
tainer. Store bait and concentrates in a locked cabinet out of
the reach of children or animals, and post appropriate warnings
on the outside of cabinet doors. If baits are stored with other
chemicals, be sure that they are packaged in airtight containers
to prevent absorption of foreign chemical odors, which will
reduce the bait's effectiveness. Carefully follow label direc-
tions on all rodenticides. Except when using permanent bait sta-
tions, remove and destroy all uneaten bait at the end of the
poisoning program.
Sound and Electronic Devices. Although rodents are easily
frightened by strange or unfamiliar noises, they quickly grow
accustomed to regularly repeated sounds and thus live in grain
mills and factories with high sound levels. Ultrasonic sounds,
those above the range of human hearing, have very limited use in
rodent control because they are directional and do not penetrate
behind objects. Also, they lose their intensity quickly with dis-
tance. There is little evidence that sound of any type will drive
established mice or rats from buildings.
Predators. Although cats, dogs and other predators may kill
rodents, they do not give effective control in most cir-
cumstances. It is common to find rodents living in very close
association with dogs and cats. Mice and rats may obtain much of
their diet from the pet's dish or from what pets spill.
SUMMARY
1. Try to eliminate or reduce the number of places rodents
can use for shelter. Prevent clutter in and around buildings and
structures, and keep stored feed in rodent-proof facilities.
Where practical, make structures rodent-proof. When rodents have
no place to hide or nest, they cannot thrive.
2. If rodents or rodent signs are present, begin control
efforts. Use traps or rodenticides to reduce their numbers. Place
baits or traps in areas where rodents are active, and maintain
control efforts diligently until successful.
3. Once rodent numbers have been reduced, continue a regular
program of control to keep rodent numbers to a minimum. Maintain
permanent bait stations or traps to control invading rodents and
to keep surviving rodents from multiplying.
o
To simplify information, trade names of some products have
been used. No endorsement of named products is intended, nor is
criticism implied to similar products not mentioned.
NEW 1/87 (5M)
Figure 1. Right and wrong placement for snap traps.
Figure 2. A rodent bait box attached to the top of a pen dividing
wall in a swine facility. When used in such locations,
bait boxes must be securely fastened and out of pigs'
reach.
Figure 3 (a). A homemade rodent bait station can contain liquid
as well as solid (cereal) baits.
Figure 3 (b). A safe, effective homemade baiting station.
______________________________________________
Cooperative Extension Work in Agriculture and Home Economics,
State of Indiana, Purdue University and U.S. Department of Agri-
culture Cooperating. H.A. Wadsworth, Director, West Lafayette,
IN. Issued in furtherance of the Acts of May 8 and June 30, 1914.
It is the policy of the Cooperative Extension Service of Purdue
University that all persons shall have equal opportunity and
access to our programs and facilities.
.