The citizen., 1920-08-12

While the use Of poison is the bes
and quickest way to get rid Of rat
and mice, the odor from the dea'
animals makes the method imprac
ticable in occupied houses. Poison
may be effectively used in barns
stables, sheds, cribs, and other out
buildings.
Caution
In the United States there are few
laws which prohibit the laying o1
poisons on lands owned or controlled
by the poisoner. Hence It is all tn,
more necessary to exercise extrem,
caution to prevent accidents. II
several states notice of intention Il
lay poison must be given to persons
living in the neighborhood. Poison
for rats should never be placed il
open or unsheltered places. This ap,
plies particularly to strychnine OF
arsenic on meat. Packages contain.
ing poison should always bear q
warning label and should not be kept
where children might reach them.
Fumigation
Rats may be destroyed in their bur.
rows in the fields and along river
banks, levees and dikes by carbon bi.
sulphid. A wad of cotton or other
absorbent material is saturated with
the liquid and then pushed into the
burrow, the opening being packed
with earth to prevent the escape OF
the gas. All animals in the burrow
are asphxyiated. Fumigation in
buildings is not so satisfactory, be-
cause it is difficult to confine the gases
Moreover, when effective, the oder
from the dead rats is highly objec.
tionable in occupied buildings.
Chlorine, carbon monoxide, sulphur
dioxide and hydrocyanic acid are the
gases most used for destroying rats
and mice in sheds, warehouses, and
stores. Each is effective If the gas
can be confined and made to reach
the retreats of the animals. Owing
to the great danger from fire incident
to burning charcoal or sulphur in
open pans, a special furnace pro-
vided with means for forcing the gas
into the compartments of vessels or
buildings is generally employed.
Hydrocyanic-acid gas is effective in
destroying all animal life in build
ings. 1t has been successfully used
to free elevators and warehouses Of
rats, mice and insects. However, it
is dangerous TO human life that the
novice should not attempt fumigation
with it, except under careful instruc-
tions. Directions for preparing and
using the gas may be found in a
publication entitled "Hydrocyanic-
Acid Gas Against Household Insects, !"
by DR.. L. o. Howard and Charles H.
Popenoe.
Rat Viruses
Several heterogeneous, or bac-
terra, found originally in diseased
rats or mice, have been exploited for
destroying rats. A number Of these
so-called rat viruses are on the
American market. The Biological
Survey, the Bureau Of Animal In
dustry, and the United States Public
Health Service have made careful in
vestigations and practical tests Of
these viruses, mostly with negative
results. The cultures tested by the
Biological Survey have not proved
satisfactory.
The chief defects to be overcome
before the cultures can be recon-
mended for general use are: /. The
virulence is not great enough to kill
a sufficiently high percentage Of rats
that eat food containing the micro
organisms. 2. The virulence de-
creases with the age of the cultures.
They deteriorate in warm weather
and in bright sunshine. 3. The dis
eases resulting from the microor-
ganisms are not contagious and do
not spread by contact Of diseased
with healthy animals. 4. The COM
parative cost Of the cultures is too
great for general use. Since they
have no advantages over the common
poisons, except that they are usually
10 man and other animals,
they should be equally cheap; but
their actual cost is much greater.
Moreover, considering the skill and
care necessary in their preparation,
il is doubtful if the cost can be great
ly reduced.
The Department Of Agriculture
therefore, does not prepare, use, or
the use Of rat viruses.
(Continued Naxt Waakl