View report page

76
dealt with under the supervision of the Department, and all necessary information was
given to representatives who called for advice. The attached table shows that of the 1,153
buildings visited during the year, 479 were found to be rat infested, and in these rat proofing
work was carried out at 441. This work chiefly consisted of wiring area gratings, ventilators,
roof openings, and the stopping of rat holes in walls and floors. Other necessary
work, such as the removal of wooden floors from basements and substituting concrete, the
stripping of internal walls of the woodwork, such as matchboarding, wainscoting and panelling—behind
which rats nest and breed—the cementing of walls and the removals of ceilings
in certain cases, could only be done to a very limited extent, because it would not be considered
a reasonable request to ask an occupier to carry out this expensive work in a building
which he does not own.
Rat Week.—No special effort was put forward during Rat Week. Rat repression work
in the City being continuous, it is difficult to see what advantage can be gained by distributing
circulars to firms who are doing their utmost (in their own interests) to deal adequately
with the rat nuisance. Moreover, in previous years, some of these firms have expressed
their irritation on receipt of those circulars.
Virus.—The subject of virus received attention in 1913, when the virus in use by
certain tenants at the Central Meat Market was examined by the City bacteriologist, who
reported that the particular virus was inert, though it was stated to contain a modified
Lœffler’s bacillus (possibly the bacillus typhi murium, of Lœffler).
The virus question was again enquired into in 1920, when three samples were obtained.
One proved to be identical with Gærtner’s B. enteritidis, the second resembled Gaertner's
bacillus and the third was similar to the first. The conclusion arrived at, after considering
the subject at some length, was that Gærtner’s bacillus was not a natural inhabitant of the
intestine of either rats or mice, but that both these animals might be infected by these organisms,
and the result might be death or recovery ; the animals might survive as carriers,
and it was suggested there was a possibility of a carrier animal gaining access to
food and contaminating it. The question, therefore, arose whether the use of virus
should be prohibited. It has been the practice of this Department not to encourage
the use of bacterial preparations in City premises, but no power exists which would enable
the Corporation to prohibit their use.
Traps.—Various kinds of traps have been used, the ordinary cage trap, the eel-pot,
the round wire and other types of wire traps. None of them are very successful, and some
are constructed of wire so fine that captured rats are able to force the wires apart and escape.
Better results have been obtained with break-back traps and varnish traps, the latter being
now in general use and the most successful of all.
Poisons.—Many kinds of poisons are used in the City by the poisoners employed by
City firms, e.g., Strychnine, Arsenic, Plaster of Paris, Magnesium Sulphate, Squill, Phosphorus,
Barium Carbonate, etc. There is no law to control the use of many deadly raticides,
but the dangers of Strychnine, Arsenic, Phosphorus, are pointed out to the users.
Red Squill Extract is the poison chiefly recommended on account of its being extremely
toxic to rodents and its comparative harmlessness to domestic animals.
In April, 1920, a lengthy report on rat repression was submitted in printed form to the
Corporation. This dealt in a fairly comprehensive manner with the natural history of the
rat, the circumstances which contribute to the prevalence of rats in the City, and the available
methods for attacking the problem. Several other reports have been submitted at different
times, and the chief conclusions arrived at are as follows:—
(1) Rat infestation, if uncontrolled, will depend upon the amount of food which is
available. Rats increase to the limits of the means of subsistence. Available food is,
therefore, an important factor in rat increase.
(2) The increase can be to some extent prevented by—
(a) Rendering premises rat-proof and thereby preventing casual infestation. Such
means include satisfactory construction of drains and adequately guarded
openings of basements, and doors; also internal improvements in premises,