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70
In answer to this I would state that technical officers of the Rodent
Division, Ministry of Agriculture and Fisheries, are confident that
poisoning campaigns carried out by adjoining local authorities in
the London area over the past nine years have undoubtedly resulted
in a considerable reduction of rats in the sewers and in a proportionate
decrease of surface infestation. The first sewer treatment ever
carried out in London was, I believe, in 1943/44 when the Ministry
of Food, who were then responsible for rodent control at central
government level, focused attention on the rat problem in order to
conserve the nation's food supplies.
Measures taken to destroy rats, however successful, have only
a limited and temporary effect. In this respect, most people know
that rats are prolific, but few are aware of the rapidity with which
their numbers increase.
The usual litter varies from 5 to 14, and 16 is not uncommon.
Rats breed throughout the year, although most young ones are
born in the Spring. The period of gestation is about 21 days, and
impregnation may be renewed within a few hours of the birth of a
litter. They begin to breed when only three or four months old,
and continue to breed five or six times in the year. Technical
research has shown that a pair of rats and their descendants may
produce, in the course of 12 months, well over 1,000 offspring.
There is no positive cure or remedy for the rat problem in
Leyton. The best we can do is keep the numbers down to a minimum
by constant vigilance and attack. Unfortunately the difficulties
associated with rodent control and the measures taken and methods
employed for dealing with it are not readily appreciated by the
public. It is one of the difficulties of this type of administration
that we are not often in a position to offer definite proof of the
efficiency of our efforts. The results of this work, like so many other
aspects of environmental hygiene, are not easily seen, and in consequence
doubt is often cast on the efforts of those whose job it is to
combat the evils of bad housing, bad drainage, and allied problems.