View report page

During the year numerous complaints of the presence of biting
mosquitoes were received from residents of Whitton and the Twickenham
Road area of Isleworth. This complaint was investigated first in 1939
when the mosquito was identified as culex molestus. Some particulars
of this mosquito are given below:-
The most common mosquito in Britain is culex pipiens which
does not bite man. In 1930 Roubaud in Paris described what he considered
to be an abnormal variety of culex pipiens in that it attacked
human beings. In 1934 this variety was detected at Hayling Island by
Marshall and Staley who showed that it was a distinct species and
suggested the name, culex molestus. In 1935 it was found in
Westminster; in 1938 in Battersea, Bermondsey, Chelsea, Deptford and
Greenwich; in 1939 in Isleworth and in 1940 in stagnating water in the
London Underground Railways. This last observation confirmed previous
indications that the primary breeding place is in dark and warm underground
situations. In 1943 culex molestus was found in West Ham,
Richmond and Twickenham. A careful detailed examination by an expert
is necessary to distinguish the adult forms of culex molestus and culex
pipiens. The larvae are identical in appearance and the usual method
of identifying these species is to watch the behaviour of the adult
mosquitoes reared from the larvae. Adults hatched from molestus larvae
will mate and lay eggs without having had a blood meal whereas in the
absence of a blood meal adults hatched from pipiens larvae remain
sterile. Thus it may take some weeks to ascertain what type of
mosquito is breeding in any larva-infested water.
Since 1939 larvae from the following sources in the Borough
have been identified as culex molestus warm dark places under
boilers, underground passages in a sewage works and tanks, water butts,
ponds etc. in gardens and allotments. Constant attention has been
given to Mogden Sewage Works but on one occasion only (1943) has culex
molestus been found breeding there. Larvae from many sources have been
collected and the behaviour of the adult mosquitoes hatched therefrom
observed with a view to confirming or otherwise the presence of culex
molestus. To date this mosquito has been found most frequently in
allotment tanks. These are probably secondary infestations and the
main, and probably underground, breeding place has yet to be found.
In all this work we have had the advice and assistance of Mr. J.P.
Marshall, Director of the British Mosquito Control Institute. While
the search for the primary breeding place continues all allotment
tanks, water butts, garden ponds, gravel pits, etc. should be treated
with paraffin or D.D.T. This will help to control the breeding of
this fierce, pers istent and vicious human biting mosquito.
On the whole the health of the Borough was maintained during
1945. The fluctuation In the Infant mortality rate has been the most
disturbing feature of the war years. This report deals with certain
health matters only and though there Is no reliable information available
it must be admitted that many of the population, though not unfit
for work, are far from enjoying perfect health. "Health is won by a
way of life rather than a bottle of medicine" and a national healthservice,
to be effective, must be directed towards prevention as well
as cure. Social, industrial and environmental conditions which
predispose to ill-health must be removed and the active co-operation of
individual citi zens developed. Without this co-operation all other
measures will fail and education Is the chief method by which this
interest can be fostered.
The staff of the Department have given loyal and generous
service. I am grateful to the Chairman and Members of Committees for
their consideration and support and to my colleagues in other Departments
for their co-operation.
I remain,
Your obedient servant,
A. ANDERSON.
5.