28 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
and in the adjoining streets, in which depressions either natural or dug out by the 
natives occur, in which mosquitoes breed. In these compounds, also, I found many 
old crab holes containing larvae. Owing to the comparative evenness of the surface, 
pools formed in this neighbourhood cannot exist for long after the rains have ceased ; by 
the middle of November there were only one or two natural breeding places to be found. 
The level of this swamp is being rapidly raised by the deposition ot sand taken from 
the beach ; already the area which has been completed has proved a success. The 
native compounds built on it were comparatively free from water during the rainy 
season last year. The remaining swamp to be mentioned is a small one extending 
from the back of Government House to just beyond the telegraph station, and is 
limited on the town side by Picton Road. In this swamp water collects in the rainy 
season and lasts for some time after the rains have ceased, especially in the drain 
running down its centre which has been previously described ; pools and depressions also 
occur amongst the grass. This swamp supplies Government House, the Hospital, 
and other European quarters in this neighbourhood with a considerable number ot 
mosquitoes. The mosquitoes found breeding in the above swamps were in order of 
frequency : A. costalis (the larvae of this mosquito were found in disused crab holes 
containing water on several occasions, principally in Half Die swamp), Culex halassios, 
Culex duttoni, Culex tigripes, A. pharoensis (rare), Culex euclastos (rare). 
The swamps described above are not flushed by tidal water owing to the ow 
wall which surrounds the town in their neighbourhood, and also because he siv :e 
gates are only opened at ebb tide ; still a little tidal water gains entrance int- the main 
channel by leaking through the gates. 
There is a considerable variation in the number of breeding-places in Bathurst 
according to the season of the year. In October, when I landed there, the rainy season 
was rapidly drawing to a close, only a few heavy showers occurred at the beginning of 
the month. Altogether there was 3-81 inches rainfall. At the beginning ot this 
month all the breeding-places described above were present, at the end of the month 
practically all the natural and many of the artificial (drains and boats) were dried up. 
Accompanying this drying up of the breeding-places there was a slight diminution 
of mosquitoes in some parts of the town (Government House, Hospital, Telegraph 
Station), but no marked diminution in factory compounds or native quarters. From 
November onwards, until the commencement of the rains at the beginning of June, 
the only places in which mosquitoes can breed are wells, tubs, and other articles for the 
storage of water in compounds, in the tidal water in some of the main drains near the 
sluice gates, chiefly in Wellington Street, and in the three pools near the cemetery. 
An examination of the mangrove swamp at the back of the town was made on several 
occasions, but no breeding-places were found, though some puddles were present 
which appeared to be suitable. It is very probable that the absence of breeding-places 
in the mangrove swamp is due to the ebb and flow of the tide and the presence of fish. 
