Look along wall/floor junctions, on
pipes and ceiling joists, and on sill
Outdoors, rat burrows may be found singly or in
plates where rats swing around
groups along foundation walls, under slabs and
dumpster pads, in overgrown weedy areas, beneath
obstacles. Grease marks are also found
debris, and in embankments.
at regularly used openings in walls,
Look for a burrow opening that is free
floors, and ceilings.
of dirt, leaves, and debris, often with
smooth, hard-packed soil.
Look for rubmarks at the opening, and
Outdoors, rats constantly travel the same route;
soil pushed out in a fan-shaped pattern.
their runways appear as beaten paths on the ground.
Fill the opening with a small amount of
Look next to walls, along fences, under
wadded-up newspaper or a few leaves
bushes and buildings. Indoor runways
and cover it with loose soil. If the rats
(harder to identify) may appear as well-
are still using the burrow, they will
polished trails, free of dust.
reopen and clear the hole overnight.
A rat's foot print is about three-quarter inches
Cats and dogs may excitedly probe an area of
long, and may show four or five toes. Rats may also
floor or wall where rats are present, especially if the
leave a "tail drag" line in the middle of their tracks.
rats have only recently invaded.
Look in dust or soft, moist soil.
Place a tracking patch in suspected rat
areas to show footprints. [A tracking
Heavy infestations have a distinctive odor which
patch is a light dusting of an inert
can be identified with practice. The odor of rats can be
material such as clay, talc (unscented
distinguished from the odor of mice.
baby powder), or powdered limestone.
Don't use flour, which may attract
Estimating Rat Numbers
insect pests. A good patch size is 12x4
It's not easy to tell how many rats are infesting a
inches.] Apply patches in suspected
site. As a rough guide, you can use rat signs to
runways and near grease marks. When
characterize the population as low, medium, or high.
inspecting tracking patches, shine a
In rat-free or low infestation conditions,
flashlight at an angle that causes the
no signs are seen. The area either has
tracks to cast a distinct shadow. [Note
no rats or was invaded recently by a
that a tracking patch is not the same as
tracking powder. Tracking powders are
With medium infestation, old droppings
diluted rodenticides in dust form,
and gnawing can be observed. One or
tracking patches use nontoxic dust. Do
more rats are seen at night; no rats are
not use a tracking powder to make a
seen during the day.
When there is a high infestation, fresh
droppings, tracks, and gnawings are
common. Three or more rats are seen at
A rat's incisor teeth grow at a rate of about five
night; rats may be seen in the daytime.
inches per year. Rats keep their teeth worn down by
continuously working them against each other and by
gnawing on hard surfaces.
CONTROL AND MANAGEMENT
Look for gnawing damage as evidence
Most successful rat control programs use a
of a rat infestation. Gnawed holes may
combination of tools and procedures to knock down
be two inches or more in diameter.
the rat population, and to keep it down. Methods used
Inspect floor joists, ceiling joists, door
combine habitat alteration and pesticide application.
corners, kitchen cabinets, and around
Some of the tools, such as baiting and trapping, are
pipes in floors and walls.
lethal to the rat. Some tools are not; rat-proofing, for
example. Sometimes applicators recommend changes
Roof rats, in particular, often nest or store food
that their customers need to make, such as increasing
in the attics of buildings. Roof rat nests may also be
the frequency of garbage pickup or making building
found when dense vegetation is trimmed.
Module Three Chapter 2, Pg 6