BENGAL PUBLIC HEALTH DEPARTMENT.
Preliminary Report of a Malaria Survey of Calcutta and Environs by M. 0.
Tirunarayana Iyengar, B. A., Entomologist to the Department of
Malaria Research, Bengal.
The author has conducted a mosquito survey of Calcutta and its environs
during the past two years and this paper deals with the results, more
especially from the point of view of sanitation and disease-prevention. No
thorough survey of the culicid fauna of Calcutta has up to now been made.
Previous work in this direction has either been too local or admittedly
incomplete. Stephens and Christophers made some observations in regard
to Calcutta anopheles during the year 1900. Since then, Sir Leonard Rogers
and Dr. U. N. Brahmachari have also made certain observations of the ano-
phelines of the city. Dr. Brahmachari made periodic observations of the
anophelines breeding in the Campbell Hospital tank. During 1912-13
Major McGilchrist conducted a Stegomyia survey of the Port of Calcutta,
but this is far from complete as it was conducted for a few months only, and
that at a period, viz., December and January, when the Stegomyias had
practically stopped breeding. The surveys of Paiva and Nandi, chiefly in
regard to Stegomyia, were concerned only with certain parts of Calcutta. In
1914, Major Christophers pointed out the necessity for a complete scientific
survey, and suggested that such a survey should be undertaken extending
over five years. This proposal, though endorsed by the conference convened
for the purpose of framing a " scheme for securing better sanitary control
over the Port of Calcutta and environs," has not yet been carried out. This
paper is the result of the author's attempt to make a survey of Calcutta from
the point of view of mosquito-borne diseases.
Kidderpore.—Various parts of Calcutta have been surveyed. The first
work undertaken was in the area of the new docks at Bracebridge Hall near
Kidderpore. This area was surveyed in great detail during 1917-18, every
species of mosquito found here being identified. The area, which is 4 miles
by 3, contains innumerable collections of water. Few of the numerous ponds
and pools which afforded plentiful facilities for the collecting entomologist,
were found free from mosquito larvae.
Six species of anophelines are very common in the area, viz., Anopheles
rossi (Giles), A. barbirostris (Van der Wulp), sinensis (Wied), jamesi (Theob),
fuliginosus (Giles) and listoni (Liston). The variety of A. listoni is not the
type species but the variety described by Theobald as var. alboapicalis. This
variety is more common in Bengal than the type species, and in some places,
as in the Dooars, both kinds occur. A single specimen of A. jeyporensis
(and one of what I believe to be a variety of A. gigas) were also collected.
A winter variety of A. jamesi, comparable to the adeyi variety of
A. fuliginosus, was also found, but, as the type specimens were all des-
troyed by mites when I was away from duty, the publication of this descrip-
tion has' been withheld. As regards the non-anophelines occurring in
Kidderpore we have about eleven species, including Desvoidea obturbans
(Walker), Stegomyia fasciata (Fabr), Radioculex clavipalpus (Theob),
Leucomyia gelida (Theob), Culex impellens (Walker), C. fatigans (Wied),
C. concolor (Desvoidy), Mansonioides annulifera (Theob), Aedeomyia squam-
mipenna (Arri), Mimomyia minuta (Theob) and a species not yet identified.
The Stegomyias occur wherever coolie lines exist. The various other species
occur in less inhabited portions of the area under survey.
Other suburbs of Calcutta.—Other parts of Calcutta have not yet been
surveyed in such detail as Kidderpore. and the work so far done relates
especially to the anophelines present. Much attention has not yet been paid
to culicines other than Stegomyia. Stegomyia is plentiful in some localities
and is found to occur more frequently in thickly populated parts like Entally