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Chemist are sent to each local authority concerned and so far the
reports of samples taken in Wembley have been generally satisfactory.
Much work, however, still remains to be done to effect the
desired improvement of the condition of the local river and
streams but it is doubtful whether it will ever reach such a
condition as to be able to support fish life; at any rate not for
some years to come.
11. RODENT CONTROL. The Rodent Control Service, for
which a 50% grant is obtained from the Ministry of Agriculture
and Fisheries, continued to operate, the service being confined to
dealing with infestation by rats and mice. A staff of three
"Ministry trained" assistants remains the same as in the previous
year. No charge is made to householders in respect of treatment
at private dwelling houses but in all other cases a charge is made
on a time and materials basis. In spite of the comparative nearness
of the Borough to the Port of London no ship rats (Rattus
rattus) have been found in Wembley. 696 premises were found
to be infested by rats or mice and 728 premises were treated; the
reason for the apparent discrepancy in these figures being that a
number of premises found to be infested late in the previous year
were treated in 1952.
It has been possible during the year to give an extended trial
in the use of Warfarin for dealing with both rats and mice.
Warfarin, which is a blood anti-coagulant and does not act as a
poison in the ordinary sense, is mixed in minute doses with medium
oatmeal and used as a rat and mice bait; mice, incidentally,
requiring a stronger dose than brown or common rats. Its properties
are cumulative in effect in contra-distinetion to the usual
rat poisons which are lethal following the ingestion of one
adequate dose. One dose of Warfarin bait will not prove fatal
and it is necessary that rodents should be fed over a period before
its lethal properties become effective. These properties might at
first sight appear to be disadvantageous but there are a number
of advantages which accrue from its use. There is no prejudice on
the part of animals who have once tasted the bait as can often
arise in the case of other poison baits where animals have had a
sub-lethal dose. They will continue to feed on Warfarin baits
until they prove fatal and there is apparently no pain. Baiting
with Warfarin can be commenced at any time without the customary
pre-baiting and the baits do not show the same tendency
to go mouldy as with other baits. With the older baiting
methods poison is only put down on one day of the week and the
residue removed the next day so that the chances of rodents
missing a fatal dose are greater. Warfarin baits also provide
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