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number of surface infestations by rats, this is due directly to the system
of testing drains at premises where rats are seen to gain access from
below ground, in many cases the drain is found defective, and after
repair or reconstruction the rats are completely eradicated and reinfestation
rarely occurs. It can safely be stated that the majority of rat infestations
in Chelsea are the result of defective drains, although this year has shown
an increase of complaints traced to rats escaping from sites where buildings
have been or are being demolished, and no effective steps taken by the
contractor to seal off the disused drains.
In previous years poisoning campaigns to rid the sewers of rats have
been carried out at six monthly intervals with the assistance of the sewermen
of the Borough Engineer's Department using a variety of both bait bases
and poisons. Results have been rewarding and the rat population of the
sewers has been controlled at a low level. However this year it was decided
to change this method and use direct poison, Fluoracetamide. This involved
four treatments over the year but being a direct treatment did not involve
additional labour as the necessity to prebait was avoided. The first
three direct poisoning applications took place in April, July and October.
The fourth treatment due in December had a prior unpoisoned bait test to
check by the amount of bait uptake the success or otherwise of the previous
three treatments. The test baits were laid according to plan, but
unfortunately owing to weather conditions and the impossibility of removing
manhole covers by reason of ice and snow, only a small proportion of checks
could be made and the final poisoning campaign could not be carried out.
However where checks were made there were very few bait takes recorded
and in view of this information together with the reports of sewer workers
and rodent officers I have every reason to believe the new treatment an
unqualified success. A similar treatment is programmed for 1963, and
given more reasonable weather conditions it should be possible to give a
more factual result than in the present year.