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Three Rodent Control Assistants, all of whom were trained
at the Infestation Branch of the Ministry of Food, have continued
to be employed in this service. Although the number of premises
which has needed to be visited remains much the same as in previous
years, the size of infestations has materially decreased.
There has, however, been an increase in the number of complaints
regarding the presence of mice. This increase in complaints does
not necessarily mean that there has been an actual increase in the
mice population, but is possibly due to the general public becoming
more conscious of the need for mice extermination, both from the
point of view of damage to foodstuffs and for hygienic reasons.
The addition of Antu to the list of approved poisons is welcome,
as it has been felt for some time that an additional poison would
be valuable in those instances in which rats have shown prejudice
against the poisons in general use. No observations can be made
in this year's report upon its use as approval was only forthcoming
at a date in 1950. A summary of work done is given in
the statistical appendix.
6. MOSQUITOES. During August and September there were
two manifestations of mosquito activity which engaged the attention
of the Department.
In the first a number of complaints were received from a more
or less restricted area in the Alperton Ward that residents were
suffering from mosquito bites. This area was in close proximity
to a canal, but no evidence could be found that this afforded a
breeding ground; indeed, the canal was teeming with small fish
at the time and there would be little likelihood of mosquito eggs
or larvae surviving. Attention was also given to the possibility
of mosquitoes breeding in artificial ponds in gardens or stagnant
water of any kind. Specimens of the mosquitoes were collected
and sent to The Malaria Research Station, Horton Hospital,
Epsom, Surrey, for identification. Some of them were identified
as Culex Molestus, a species known to bite human beings, whilst
the remainder were Culex Pipiens, a comparatively harmless
variety. When it was known that Culex Molestus was responsible,
it became apparent that a fresh search would be needed to discover
the breeding ground, in view of its preference for breeding
in darkness or semi-darkness. Publicity was therefore given to
the matter in the local press, urging residents to look at water
tanks and gullies—in fact, any place or receptacle containing
water which was in semi-darkness.
Ultimately, mosquitoes were discovered by one of the sanitary
inspectors to be breeding in quite large numbers in disused air
raid shelters, and confirmation was obtained that the larvae belonged
to the species Culex Molestus.
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