Rodents
The most persistent rodent pests in schools are the house mouse, roof rat, and Norway rat. Whitefooted,
deer mice, and voles (meadow mice) may also be troublesome. Rodents damage stored items,
consume and contaminate food, and serve as reservoirs of several diseases. Most rodent problems can
be prevented with landscape maintenance, good sanitation, pest-proofing, and monitoring with traps to
catch them before they become an invasive pest. Rodenticides are not generally recommended except
to reduce very high populations. Rodenticides may only be used in locked bait boxes serviced by a
licensed applicator.
Most rodent problems can be prevented with landscape maintenance, good sanitation, and rodent proofing.
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Norway rats are common pests.
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Sanitation
- Inspect the school grounds for food sources. Remove edible plants, fallen fruit and nuts, and animal feces.
- Keep lids on trash cans and close dumpsters at night. Cover the drainage holes in dumpsters with wire mesh to keep rodents out.
- Remove debris, lumber piles, firewood, trash, and discarded items to reduce shelter for rodents.
- Trim all vegetation at least 3 feet from all buildings to decrease cover for rodent runways and prevent
hidden access to buildings.
- Break up long stretches of dense vegetation or tall
ground cover that allow rodents to travel long
distances under cover.
Rodent proofing
Also called exclusion, rodent proofing involves
tightening a structure so that rodents cannot get in. A
young rat can squeeze through an opening as small as
1/2-inch. Any opening that a pencil can fit through will
admit a mouse. Inspect and seal doors, door sweeps,
weather-stripping, cracks, gaps, and other openings
where rodents may enter a building.
Traps
Trapping is preferable to using rodenticides for
controlling rodents on school grounds. Traps can be
used in situations where poisonous baits are not
allowed; they also avoid the odor problem of rodents
dying in inaccessible places. School staff do not need a
license to use mechanical traps for rodent control.
Rodents often run along edges, and they routinely
follow the same runways. Identifty runways by
sprinkling a fine layer of flour or baby powder in
suspected areas to observe tracks. Place traps along
walls and runways, 6-10 feet apart, especially where
objects such as a box or appliance will guide them into
the trap. Roof rats and Norway rats usually fear new
items in their environment; they avoid them for several
days. Keep all rat traps in place for at least 1 week
before moving them.
Traps used for rodent monitoring or management
should be checked daily. Traps or other surfaces
contaminated with rodent urine or feces should be
properly disinfected or disposed of.
Baits
The bait depends on the rodent. House mice
prefer peanut butter, gum drops stuck to the trigger, or
rolled oats or bird seed sprinkled on the trap. When
food is abundant, nesting material, such as a cotton
ball tied to the trigger, can be effective. Roof rats
prefer peanut butter, pieces of fruit, or shelled nuts.
For Norway rats, use raw or cooked meat, fish
(sardines are excellent), or peanut butter.
- Snap Traps. Both the classic rodent wooden trap and
the newer metal clothespin design kill trapped animals
quickly. Snap traps should be placed in locked rooms or
other areas not accessible to children or in locked, tamperresistant
containers securely attached to a surface so that
the container cannot be picked up or moved.
- Live traps. Several types of live traps are available.
Some catch a single rodent, others reset themselves to
capture several. Check live traps regularly to prevent the
captured rodents from starving or dying of thirst and
creating an odor problem. These traps may be
expensive and the live animals must be dealt with.
Rodents should not be released to the wild.
- Glue boards are most effective against juvenile mice
in dry, dust free areas. Although rat-sized glue boards are
available, captured rats can often pull themselves free.
Use a tack, a small nail, wire, or double-sided tape to fix
glue boards to ledges, pipes, or rafters. Do not set them
near open flames or above carpet. These traps should not
be set where children or domestic animals will come into
contact with them. Although they are not hazardous to
children, an encounter with a glue board can create a
frustrating mess. Clean hands with room-temperature
cooking oil. Clean hard surfaces with paint thinner or
mineral spirits.
Ultrasound Devices
Ultrasonic devices create a loud noise, above the
range of human hearing that is unpleasant to rodents.
Rats and mice quickly adapt to the sound by avoiding
it. Because the extremely high notes are easily
reflected, any object in the area can create a sound
shadow. Rodents shift their activity to these low noise
shadows. Although the expense of the devices may not
be justified, this behavioral change can be used to
guide rodents into traps that are purposefully set in
low noise locations.
Chemical control
In situations where trapping alone cannot
resolve rodent problems, anticoagulant baits are
usually effective. Because rodenticides may be
highly toxic to humans, they should only be used in
secure locations and contained in tamper-resistant
bait boxes. As with all esticides, it is a violation of
Maine law for unlicensed persons to use rodent
poisons in schools. Be sure your pest control
professional follows these guidelines for using
rodent poisons:
- Use rodent bait stations that are locked and firmly
anchored.
- Place bait stations in areas inaccessible to children.
- Place rodenticides in the baffle-protected feeding
chamber of the box. Never place bait in the runway.
- Bait stations should be monitored and serviced
regularly, and removed promptly when rodents are
no longer using them.
- Have your licensed applicator provide a map
showing locations of all traps and dates of service.
Printable Version [PDF]
Additional Fact Sheets:
IPM Principles for Rodent Control [Harvard]
Rodent Management for Schools [School IPM Tool Kit PDF]
Rat IPM Plan [Texas A&M]
Rat and Mouse Management for Schools [Minnesota Dept of Agriculture]
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