An inspection using a powerful flashlight just
Rats usually begin foraging just after dark. Most
after dark is the best way to see rats. Dead rats are
of their food gathering occurs between dusk and
signs of a current or past infestation. If all that are
midnight, but short bursts of restlessness and activity
found are old dried carcasses and skeletons, it may
can occur anytime, day or night. Rats commonly travel
mean an old infestation. Many fresh carcasses are an
100 to 150 feet from their nest looking for food and
indication that someone may be baiting the area
water and patrolling their territory. It is not unusual
currently. If rats are actively observed during the day,
for a colony of rats that nests outdoors to forage inside
the rat population is probably high.
a building 100 feet away.
Outdoors, Norway rats usually nest in burrows
When a building is quiet, squeaks and fighting
noises, clawing and scrambling in walls, or gnawing
dug into the ground. The burrows are shallow (less
than 18 inches) and usually short (less than three feet),
sounds may be heard.
Use a stethoscope or electronic listening
with a central nest. Extra "bolt holes" are used for
device to help pinpoint activity.
emergency escapes. They are hidden under grass or
boards or lightly plugged with dirt. Burrow openings
are two to four inches in diameter. Indoors, Norway
A single rat may produce 50 droppings daily.
rats nest inside walls, in the space between floors and
Roof rat droppings are generally smaller (half-inch)
ceilings, underneath equipment, between and under
than Norway rat's (three-quarter inch). The highest
pallets, and in crawl spaces, storage rooms, and any
number of droppings will be found in locations where
cluttered area that is normally unoccupied. Norways
rats rest or feed.
prefer to nest in the lower floors of a building.
Determine if a rat population is active
Roof rats commonly nest above ground in trees --
by sweeping up old droppings, then
particularly untrimmed palm trees, and in piles of
reinspect a week later for new
wood or debris, vine-covered fences, and stacked
lumber. Overgrown landscaping is also a prime nesting
Look at the appearance of the droppings
area. Roof rats will sometimes nest in burrows if
to determine if rats are currently active.
above-ground sites are limited and Norway rats are not
Fresh rat droppings are black or nearly
nesting in the area. Indoors, roof rats prefer to nest in
black, they may glisten and look wet,
the upper levels of a building in the attic and in ceiling
and they have the consistency of putty.
and attic voids near the roof line. But at times they
After a few days or a week, droppings
also nest in the lower levels of a building as do
become dry, hard, and appear dull.
After a few weeks, droppings become
Both species also nest in sewers and storm drains,
gray, dusty, and crumble easily. [Note
and both on occasion can be found in highly unusual
that sometimes old droppings moistened
nest sites. Both Norway and roof rats can have several
by rain may look like new droppings;
"hotel" nest sites in an area. A rat may spend a week
however, if crushed, they will crumble
in its home base and then move for a day or two into
and do not feel like soft putty.]
a secondary "hotel" nest site. Norway rats have been
shown on occasion to have a home range of up to 20
acres when these secondary nest sites were included in
Both wet and dry urine stains will glow blue-
white under an ultraviolet light (blacklight).
Portable ultraviolet lights are used in
the food industry to identify rat urine on
food items. Other substances besides rat
Rats give many signs that they are infesting an
urine also glow, w h i c h c a n b e
area. Inspection will determine if a site is infested, and
confusing, so proper use of this
will identify where rats are feeding and nesting, their
inspection method takes practice.
patterns of movement, the size of the population, and
the extent of the infestation. This helps the pest control
technicians decide what control measures to use, where
Oil and dirt rub off of a rat's coat as it scrambles
and how to use them, and how much effort is needed
along. The grease marks build up in frequented
to put the program in place.
runways and become noticeable.
Module Three Chapter 2, Pg 5