IV. SOME POINTS ON THE BIONOMICS OF ANOPHELES 
Breeding-places. — Throughout such an extensive country as Nigeria, it was 
natural to expect considerable diversity in the conditions under which mosquitoes of 
this genus breed. The conditions varied roughly in the three different belts of 
country already described, and mixed conditions occurred where one belt emerged 
into the next. 
In the region of mangrove swamps the native dug-out canoes are almost 
entirely the habitat of Anopheles larvae and pupae, for instance at Bonny, Okrika, 
Opobo, Bakana Town. 
The canoes containing larvae are generally old and unused, and drawn up on 
to the foreshores of the rivers or the edges of the creeks into the neighbourhood of 
the native huts. There are, in places, a considerable number of these, which are 
now and then augmented by the addition of other canoes during a period of rough 
' sass ' weather. They are always more or less full of water according to the rainfall, 
and many have a green (protococcus) growth on their sides, or contain algae. 
Only occasionally are ' puddles ' containing larvae to be found in these man- 
grove districts, and it may be mentioned here that quite as often Anopheles larvae are 
found in water in the bottoms of broken gin bottles, in old calabashes, on the tops of 
barrels, in tubs, and old iron pots. 
In the neighbourhood of European dwellings in this district, consisting 
mainly of those of Government officials and traders, and usually built on made sites, 
it is found that the breeding places of Anopheles have been ignorantly made by the 
' white man ' himself. They consisted of ' duck ponds,' cemented or tubbed in 
(larvae are, however, never found when ducks frequent these ponds), shallow wells, 
with their sides protected by a palm oil puncheon or other barrel, and occasionally 
uncovered rain barrels. In some places, e.g., round the Consulate at Opobo, the 
nature of the surface is such as to favour the formation of a small fresh water marsh, 
in the puddles of which larvae exist. 
On the small areas of fertile land, which are here and there interspersed on 
the river banks in the midst of the mangrove swamps, and on which the ' factories ' 
of the various trading companies are usually built, the breeding places of Anopheles 
consist of shallow puddles, scattered here and there, permitted by the unevenness of 
the surface and lack of any systematic attempt at surface drainage. These ' puddles ' 
are kept full of water during the wet season, and are frequent along the footpaths 
crossing the areas, and along the sides of warehouses. In fact, the presence of the 
enormous number of mosquitoes at the factories at Slave Trees, Bakana, and at 
