22 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
converted into a series of pools by the pouring in of sand, and are often blocked at 
their outlets in a similar manner, so that fish cannot gain entrance. They thus form 
excellent breeding-grounds for mosquitoes, and, as I have shown, especially for the 
malaria-bearing variety {Anopheles). The species of mosquitoes found in the drains 
of Bathurst in order of frequency are : — 
Anopheles costalis. 
Culex thalassios (in drains containing tidal water). 
Culex hirsutipalpis. 
Culex duttoni. 
3. — Weils. During the month of October I found that the wells of Bathurst 
were not a fruitful source for mosquitoes, though larvae were present in some of 
them ; still, as a whole, they did not provide extensive breeding-places. After the 
rains had ceased and as less and less water was to be found in the drains and swamps 
I observed that mosquito larvae occurred more frequently in the wells. The public 
wells, some fourteen in all, were examined at various times during October, Novem- 
ber, December, and January ; in only one (Lancaster Street) were mosquito larvae 
found. This well had become foul, chiefly from rubbish thrown into it, and very 
soon after mosquito larvae swarmed in the water. The native population almost 
universally obtained drinking water from the public wells, and water is thus being 
drawn from these wells practically all day long. It would appear from this constant 
disturbance of the water that these wells were not suitable breeding-places, as I found 
that in many similar wells in private compounds in which the water was equally good, 
though less frequently drawn, mosquito larvae were easily obtained. Fifty-five large 
private wells were examined, occurring in compounds throughout the town ; it was 
found that those wells which had good covers were almost free from mosquito larvae, 
while all the others contained larvae in quantities depending on the frequency with 
which water was drawn from them. The small shallow tub wells occurring in large 
quantities all over the town were found to contain mosquito larvae, chiefly of the Culex 
kind, in sixty per cent, of those examined during the month of October. It was also 
noticed that when one of these wells became foul, and from this cause discarded, the 
larvae occurred in greater abundance ; not a few such tub wells exist throughout the 
town. It was also noticed how very rapidly the larvae sank to the bottom of the well 
on the slightest disturbance of the water. All the wells, both public and private, were 
re-examined systematically in the latter part of December and January by the 
Sanitary Inspector with the object of determining the percentage in which mosquito 
larvae occurred. The result is given in the following table up to the time of my 
departure from Bathurst ; this includes nearly all the public and private wells, and 
probably about two-thirds of the small tub wells. 
