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the claim that rats and mice die in the open after being poisoned by virus as complaints
have been made of the nuisance of dead rats between match boarding and
walls and under floors in premises where virus has been used. As the virus question
is a serious one, I make no excuse for again referring to my printed report of April,
1920, which dealt with the subject in a comprehensive way. (A reprint of this
report for further distribution is needed as requests are frequently being made for
it.)
By a general Army Order, dated July 29th, 1919, the use of any vermindestroying
virus preparation is prohibited in all military establishments and
camps, the reasons stated for their prohibitions are:—
1.—They are apt to produce a rat population which is immune
to the action of the virus.
2.—There is a certain degree of risk of food contamination with resultant
food poisoning outbreaks.
Experience in the City has proved that both these reasons are sound. It is
regrettable that the civilian population is not afforded the protection from food
poisoning outbreaks as that which the Military Authorities afford to His Majesty's
Army by prohibiting the use of virus. It is probably only a 50 to 60 per cent,
killer and should be condemned for that reason alone.
Every known preparation of poison is used in the City and although poisons
have their disadvantages, e.g., causing rats to die in hidden places where the bodies
are not easily accessible, it is impossible to reduce their number to any extent without
them. Rat traps require very careful setting and more attention than the employees
of a business firm care to devote to them, whereas poisons are easily placed about
a building. A liquid or semi-liquid bait is the best inside a building—bread soaked
in red squill extract for instance; the rat has to eat this on the spot, it cannot be
carried away and hoarded under floors or other places of harbourage as frequently
happens with solid baits. It is very seldom that a rat poisoned with squill dies in
a hidden place and being a comparatively safe poison it is about the most suitable
and effective for occupied buildings. Very good results have been obtained by
using squill and alternating with varnish traps which are quite easily made and
give better results than wire cage traps or break-backs. Dead rats under floors,
etc., are not always easy to locate. Where there is a lath and plaster white-washed
ceiling below the floor under which the body of a dead rat lies, an examination of
the ceiling will often reveal a patch of discolouration due to moisture from the
decomposing rat having percolated. A lot of time and unnecessary removal of
floor boards could thus be saved by a glimpse at the ceiling beforehand, when the
position of the decomposed rat can at once be located if the damp patch alluded to
is seen.
Boulter, in his book "The Rat Problem" (1909), and Howell in his recentlypublished
book "Rats and How to Destroy Them" (1924), both suggest the
following method for discovering the precise spot where the body of a dead rat is
lying. In the summer month, viz., catch several bluebottle flies with a butterfly
net. Then, having closed the windows and door of the room in which there is the
odour, liberate the flies and notice where they all settle; that will indicate the
place below which the dead animal is lying.
The trouble in the City with dead rats usually arises in the winter time when
neither bluebottles nor butterfly nets are readily procurable.
Poisoning, trapping, and ratproofing are all necessary measures and it is no
use relying on one of these methods alone. That is where rat poisoners who rely
on poisons only fail to effect anything but a very temporary clearance with regard
to ratproofing. Until further powers are sought and obtained in regard to the destruction
of rats, not much work can be done, and in view of a discussion which took
place in the Court of Common Council last year, I venture to repeat the following
observations from my 1923 report:—
"It is also perhaps of interest briefly to mention the standpoints from which
rat repression is viewed by the owner and the occupier of a building since the Act
came into operation.
L