PUBLIC RECORD OFFICE
Reference :-
TITICO. 885
24 PUBLIC RECORD OFFICE, LONDON
ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC- COPYRIGHT PHOTOGRAPH-NOT TO |
12
The habits of Stegomyia fasciata here are, therefore, the same as in other parts of the world, with the important exception that it is not usual to find it breeding in miscellaneous receptacles such as old jars, cans, tins, etc., as described by Sir Rubert Boyce and other authorities.
Careful and prolonged search has been made of these miscellaneous breeding places both in this investigation and by Dr. J. C. Thomson in 1902.
In Dr. Thomson's case no fasciata at all were found, and in the present investi- gation they have only been found in these receptacles to a very limited extent.
Stegomyia scutellaris, which is to be found breeding in practically every such collection of water, here apparently occupies the place taken by Stegomyia fasciata in other parts of the world.
With the exception of a few licensed premises none of the Chinese houses in Kowloon have water laid on. All water for drinking, cooking, etc., has, therefore, to be carried from stand-pipes in the street and stored in the kitchen or yard in It is in this stored clean wooden barrels, earthenware jars (kongs), iron pails, etc.
As the water that by far the majority of finds of fasciata larvæ have been made. labour of carrying this water is considerable, the storage receptacle is not frequently emptied and cleansed; more water is simply added to what is already there. The water is also used more economically, the average amount per head being about half that used in Victoria.
The fasciata larvæ have, therefore, plenty of time to develop, and, owing to their well-known habit of going to the bottom when the water is disturbed, they are not likely to be taken out when water is removed for cooking or other purposes.
As it was not practicable to empty these barrels, etc., when searching for larve, special dippers were made, by which samples of the water could be removed for examination.
Experience, however, showed that if the barrel, etc., was full the chance of capturing larvæ was very small; much better results were obtained in receptacles which were more or less empty.
It may, therefore, be assumed that many well-filled barrels and kongs were passed as negative owing to the impossibility of catching the larvæ
Howard, Dyer, and Knab, in their well-known work "The Mosquitoes of North and Central America and the West Indies," 1912, state (page 286): "when water is poured from a receptacle inhabited by calopus (ie., fasciata) larvæ these quickly seek the bottom, and their presence may not even be suspected although the vessels be in constant use. They cling so closely to the bottom that unless the jars are tipped up so as to empty them completely, which is not usually done, nearly all the larvæ remain in the jars."
They further state (page 287) that the first Yellow Fever Commission to Vera Cruz found that, on account of this habit, the larvæ are not easily disposed of by pouring out the contents of a barrel. When the barrel or other container with thousands of larvæ is approached and slightly agitated the insects disappear rapidly to the very bottom, so that nearly all the water can be dipped out from the barrel without removing more than a few of the larvæ. The barrel may be turned upon its side, and it will be found that about 80 per cent. of the larvæ will stay in the few remaining ounces of water.
My experience in Kowloon agrees with these well-known authorities, and it is, therefore, I think, safe to assume that the finds of fasciata larvæ in stored water receptacles (barrels, kongs, etc.) in Kowloon underestimates the prevalence of these larvæ. The same, however, is probably not true of collections of water found in miscellaneous jars, pots, tins, etc., as in nearly every case these can be completely emptied and the last larvæ collected.
The results so far obtained in Kowloon would appear to indicate that, if the storage of clean water could be completely done away with by laying on a continuous tap supply into the houses, the chief breeding places of Stegomyia fasciata would be destroyed. This remedy would necessitate a sufficient supply of water, as prob- ably twice the present amount of water would be used or wasted. No cisterns should be allowed unless completely protected.
Stegomyia fasciata in the City of Victoria.-The miscellaneous jars in houses and back yards in Victoria have been very thoroughly examined, with the result that in only three cases have Stegomyia fasciata larvæ been taken.
These three finds are widely separated, being in Wellington Street. Jervois Street, and Des Voeux Road West. The miscellaneous receptacles are, therefore,
13
even less infected with fasciata than in Kowloon. Water is laid on to taps in all houses in Victoria, being in this respect the opposite to what obtains in Kowloon. For about seven months in the year the supply is continuous; in the remaining five months it is intermittent, but never less than two hours per day.
A relatively very large amount of storage receptacles are kept and are put into use during the intermittent period, but are very largely disused during the continuous supply.
At the time of my inspections the city was on the continuous supply, and any storage barrels in use were full to overflowing. It was, therefore, not practicable to make any thorough examination.
Further search is delayed till the intermittent supply is brought into force again, when a thorough search of the stored water will be made.
Junks in the Harbour of Hong Kong.-One thousand five hundred visits were made by the two police collectors to junks and Chinese cargo lighters in the harbour: no fasciata larvæ were obtained.
II. Tabanida Investigation.
In collaboration with Mr. Adam Gibson, M.R.C.V.S., Colonial Veterinary Surgeon, who originated the work, an investigation of this well-known family of biting flies has been started and is still in hand.
One thousand five hundred and eight specimens have been forwarded to the Director of the Imperial Bureau, and a preliminary list dealing with 395 of these has been received and contains the following species:
Tabanida.
1. Chrysops dispar, F.
2. C. striata, Wulp.
3. Tabanus crassus, Walk.
4. T. ditaniatus, Macq.
5. T. hilaris, Walk.
6. T. hybridus, Wied.
7. T. indianus, Ric.
8. T. jucundus, Walk.
9. T. negativus, Ric.
10. T. sanguineus, Walk.
11. Tabanus sp. nov., near birmanicus, Big.
12. Tabanus sp. nov., near inobservatūs, Ric.
According to Dr C. Kerte'sz's "Catalogue Dipterorum," Vol. 3, 1908, only one of these species--Chrysops dispar, F.-is noted as occurring in Hong Kong.
Tabanus hybridus, Wied.. is given as occurring in Macao, and Tabanus jucundus, Walk.. as in China. Two species are entirely new and are not yet described by the British Museum.
III. Epizootic Abortion.
Experiments were started in December to see if Bang's bacillus of epizootic abortion could be isolated here, and, if so, to try the effects of bacterial treatment. This work has not yet advanced far enough for report.
HAROLD MACFARLANE.
Government Bacteriologist.
15th January, 1915.
17941
(No. 70.)
SIR,
No. 15.
NEWFOUNDLAND.
THE GOVERNOR to THE SECRETARY OF STATE.
(Received 19th April, 1915.)
[Answered by No. 39.]
Government House, St. John's, 5th April, 1915. REFERRING to your despatch No. 103, of the 4th March,* I have the honour to inform you that, at the expiration of the present period of three years, namely,
* No. 11.
13
less infected with fasciata than in Kowloon. Water is laid on to taps in all in Victoria, being in this respect the opposite to what obtains in Kowloon. bout seven months in the year the supply is continuous; in the remaining five he it is intermittent, but never less than two hours per day.
the
A relatively very large amount of storage receptacles are kept and are put into luring the intermittent period, but are very largely disused during nuous supply.
At the time of my inspections the city was on the continuous supply, and any ge barrels in use were full to overflowing. It was, therefore, not practicable ke any thorough examination.
Further search is delayed till the intermittent supply is brought into force 1, when a thorough search of the stored water will be made.
Junks in the Harbour of Hong Kong.-One thousand five hundred visits were by the two police collectors to junks and Chinese cargo lighters in the harbour: sciata larvæ were obtained.
Tabanida Investigation.
In collaboration with Mr. Adam Gibson, M.R.C.V.S., Colonial Veterinary
Bon, who originated the work, an investigation of this well-known family of g flies has been started and is still in hand.
One thousand five hundred and eight specimens have been forwarded to the tor of the Imperial Bureau, and a preliminary list dealing with 395 of these een received and contains the following species:
Fabanida.
1. Chrysops dispar, F.
2. C. striata, Wulp.
3. Tabanus crassus, Walk.
4. T. ditæniatus, Macq.
5. T. hilaris, Walk.
6. T. hybridus, Wied.
7. T. indianus, Ric.
8. T. jucundus, Walk.
9. T. negativus, Ric.
10. T. sanguineus, Walk.
11. Tabanus sp. nov., near birmanicus, Big.
12. Tabanus sp. nov., near inobservatus, Ric.
According to Dr C. Kerte'sz's "Catalogue Dipterorum," Vol. 3, 1908, only
f these species-Chrysops dispar, F.-is noted as occurring in Hong Kong. fabanus hybridus, Wied., is given as occurring in Macao, and Tabanus
dus, Walk.. as in China. Two species are entirely new and are not yet ibed by the British Museum.
Epizootic Abortion.
Experiments were started in December to see if Bang's bacillus of epizootic ion could be isolated here, and, if so, to try the effects of bacterial treatment. work has not yet advanced far enough for report.
HAROLD MACFARLANE.
January, 1915.
Government Bacteriologist.
No. 70.)
No. 15.
NEWFOUNDLAND.
THE GOVERNOR to THE SECRETARY OF STATE.
(Received 19th April, 1915.)
[Answered by No. 39.]
Government House, St. John's, 5th April, 1915. REFERRING to your despatch No. 103, of the 4th March,* I have the honour orm you that, at the expiration of the present period of three years, namely,
* No. 11.
PUBLIC RECORD OFFICE
༄། ། ། ། ། །
Reference :-
mwimmimC.O. 885
COPYRIGHT
24 PUBLIC RECORD OFFICE, LONDON
ALLY WITHOUT PERMISSION OF THE PHOTOGRAPH-NOT TO BE REPRODUCED PHOTOGRAPHIC-|