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RODENT CONTROL
Normal routine investigation of complaints from the public continued
and a summary of the work done is given in the following table.
Properties inspected as a result of notification 333
Other properties investigated 242
Properties found to be infested:—
Rats (a) Major infestations.
(b) Minor infestations 198
Mice (a) Major infestations.
(b) Minor infestations 93
Infested properties treated by Rodent Operator 186
Treatments 193
Written notices served 1
SEWER TREATMENT
There are 1810 manholes in the soil and surface water sewers in the
Borough and during 1958 two major treatments for the destruction of
rats were carried out. On each occasion about two thirds of the manholes
were dealt with.
The first treatment was carried out in April and May, three visits being
made to each manhole during a period of 8 days. On the first visit soaked
bread was used as a bait and on the second and third visits the "take"
of the bait by the rats was checked and it was replaced by soaked bread
containing arsenic. In about 40 per cent. of the manholes there was
evidence that rats had eaten some of the bait and poison. In June a sample
testing and poisoning of 120 manholes, previously giving evidence of
infestation, was carried out. This time the bait and poison was oatmeal,
castor sugar, oil and Warfarin, and it was found that in 78 of these there
was still evidence of rats. A further sample of these taken later in June
revealed no further take and thus indicated a great reduction in the residual
rat population of these sewers. It was felt that six-monthly treatments
of the sewers was not sufficiently frequent, as rats not killed had sufficient
time to breed and increase considerably in numbers before the next
treatment. It was decided, therefore, to adopt a new form of treatment
using 0.25% of sodium fluoroacetate. This poison does not require
prebaiting. The first treatment over a period of two weeks covered 1,176
manholes. Direct evidence of the elimination of rats is not obtainable at
the baiting points, as this poison is effective in very small quantities.
For this reason it has been decided to carry out four treatments per year,
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