c. Shelter. Any rubbish, crack, crevice, or similar object that will provide
seclusion and protection from the elements will serve as harborage for rats. These
shelters should be removed or sealed so that the rats cannot gain access.
5-24. RODENT CONTROL PROGRAMS
Although environmental control is the most effective means of rodent control on a
continuing basis, more aggressive control programs are sometimes necessary. For
example, a commander may find that an area that has just been occupied is already
infested with rodents, a rodent-borne disease outbreak may necessitate an aggressive
control program, or adverse weather conditions may drive rodents to seek human
habitation for food and shelter. A complete rodent control program consists of five
distinct steps in a deliberate sequence.
a. Rodent Surveys.
(1) Observations. Surveys for signs of rodents should be made by the field
sanitation team regularly in order to detect the presence of rodents early. The following
signs indicate not only the presence of rodents but also the type of rodents, the
approximate number, and their location. Figure 5-14 provides a guide for estimating the
extent of rodent infestation.
Rat Signs
Light (1-20)
Medium (21-50)
Heavy (over 50)
Observed
Many; two or more
Moderate to many;
Few or moderate in
sizes; runways in
usually of two or
Tracks
number; usually all of
duty areas usually
more distinct sizes.
one size.
slick and not dusty.
Many; usually of
Some always
None or few groups
several sizes; small
observable in two to
Fresh
observed; generally
to large and in at
eight areas; usually
Droppings
all of the same size.
least six locations.
two distinct sizes.
Many; more than
Several distinct; one
None or few and
one heavily
or more, indicating
Active Runs
relatively indistinct.
traveled run.
heavy travel.
Fresh
Usually several
Many instances
None to few nightly.
Gnawing
instances nightly.
nightly.
Often one or more
None to two by day
None by day except
seen by quiet, close
Live Rats
unless harborage is
on cleanup and
observation, even
Seen
opened up.
harborage removal.
in daytime.
Figure 5-14. Table for estimating the number of rats present.
MD0535
5-23