37 
Breeding Grounds of Larvae. 
constant or occasional trickle of water running through them; 
they seem to prefer shallow water, especially where there is a 
good growth of green algae. In most cases the breeding-pools 
of Anopheles are exposed to the sun, a fair amount of light being 
essential to their well-being. Meinert says that “ Anopheles larvae 
appear in still or slightly rippled water with strong vegetation, 
as well in wooded regions as on heaths, but do not occur in 
shady woods, but must have sunshine and light, which their green 
colour indicates.” I have seen the larvae of this genus in shallow 
ponds some twelve to fourteen feet across, but smaller pools and 
puddles are most sought after by them. I have also found them 
in abundance in rain barrels in my own garden in Kent. Most 
of these have proved to be A. hifurcatus, a few A. maculipennis. 
In a paper * recently sent me by Dr. Nuttall, the localities 
in which Anopheles larvae have been found in Great Britain are 
summed up as follows: 41 captures in ponds; 36 times in 
ditches, in which the water had a scarcely perceptible flow ; 
15 times in ditches containing flowing water; 26 times in rivers 
and canals (Derwent, Orwell, Ouse, Thames, Lee, Cam, Mole, 
Exe, &c.); and 3 times in the back waters of rivers. Larvae 
were also captured six times in brackish water (twice in ditches, 
four times in pools), twice in water-logged boats, and twice in 
stone troughs. In only nine cases was it noticed that the water 
was dirty. Amongst the information collected by Dr. Nuttall, 
we find the following interesting notes : “ One larva ( maculi¬ 
pennis) caught in stream running through marsh and containing 
many prawns”; “ Very many larvae in middle of the Biver 
Thames between island and shore.” 
In the recent Report on the Malarial Expedition to the 
West Coast of Africa the breeding-places of Anopheles are 
summarised at Freetown as follows : “ Generally speaking, we 
found the larvae in small permanent pools, not liable to scouring. 
We did not find them in vessels, evanescent pools, pools liable 
to scouring, large collections of water, and running streams. 
The majority of the Anopheles pools were found in ditches by 
the side of roads and in certain localities where certain small 
streamlets ooze from the bases of the hills after rain; few were 
observed in the yards and gardens of houses.” In no cases were 
the larvae found far from human habitations, even in pools most 
suited to them, but this must not be taken to mean that they 
* “Studies in Relation to Malaria/’ I., Journ. of Hygiene, vol. i no. 1, 
1901 (p. 11, reprint). 
