22 
REPORT OF THE MALARIA EXl'EDITION. 
Blood was never found in male Culicidiv in Freetown- according with the general law. 
(4.) Haunts.- The large majority of Anopheles caught by us in dwellings were females 
whicli were generallv much gorged, and, if fed at all, were invariably fertilized ; in other words, 
the males and unfed, or onl\' slighth" fed, females did not generalh' remain in the houses during 
the daytime, or if the) did remain, kept in the roofs or other dark places where the\' were little 
observeil. On the whole, we think that only those females which are so gorged that the\' cannot 
fl\- far remain in the houses during the daA'. We observed that if a cage full of Anopheles was 
disturbed in the daytime, the insects alwa\ s struggled toward the light as if to fl\' out from the 
wintlows ; and several which escaped from the cages actually did so. On one occasion a large 
number escaped from their cage during the night in the rooms occupied by one of us -none of 
them could be seen next morning. 
Yet we ma\- be quite sure that both the males and the unfed females haunt the houses 
during the night. The invariably fertilized condition of the gorged females caught in the houses 
shows that the males must be present in the houses when the females feed — since the latter are 
often so much distended after feeding that the\- are obviously unwilling to fly even a few feet from 
the bed of their victim ; in other words, fertilization must take place within the houses. The 
unted females must, of course, resort to human habitations during the night in order to obtain their 
food at all. 
riiese tacts would seem to indicate that in Freetown, in the rainy season, the Anopheles 
resort to the houses during the night, but that all except the gorged females live elsewhere during 
the daytime — possibly sleep in the trees and shrubs. The point is of interest as tending to show 
that large numbers of Anopheles ma\' be present in a dwelling during the night, without it being 
easy to find them during the day. 
It should, however, be added, that in India males and unfed females were often found in 
the houses in large numbers b\' one of us. Possibly different species have different habits in 
this respect. 
Several old residents of the country informed us that gnats are usually very prevalent in the 
presence of much vegetation — especially long grass and undergrowth. Though it is difficult to see 
how such can favour the larvne, we can understand that much vegetation can shelter the adults of 
certain species, which may even feed on particular kinds of plants when they cannot obtain blood, 
and may consequently find it easier to live where these plants afford them both food and shelter 
than elsewhere. It must also be remembered that gnats can certainly bite birds and other 
mammalia besides man ; and that such are apt to congregate where there is much vegetation. 
On the whole, then, there is nothing improbable in the idea that the Freetown Anopheles should 
live outside the houses in the daytime. 
(5.) Proxhnit)' of breeding-pools to houses. -The gorged females are, as we observed, always 
fertilized, and must therefore probably lay their eggs a few da\ s later or perish. We often noticed 
that gravid females kept in dr)' test-tubes made no attempt to lay eggs unless a drop of water was 
put in — in which case they often deposited their eggs almost at once in the fluid. These 
observations suggest the conclusion that the females must return to water a few days after each 
