222 
V 
Culicifuge# 
In addition, certain proprietary articles, Nos. 7, 10-14, 17, 19 and 22, recom¬ 
mended as efficient in keeping mosquitoes and midges at bay, were tested as 
well as a few preparations made up by the authors. As regards these latter 
the reasons for their inclusion are varied. Nos. 8, 9 and 9 b, variants of 6 and 
9 a, were compounded with a view to checking the effect of altering the 
relative proportions of the active constituents and base. No. 15 was tried on 
account of its general high value as an insecticide; the formulae given being 
devised for another insecticidal purpose. Subsequently it was put up speci¬ 
fically as a culicifuge—No. 15 a. Nos. 18 and 20 were given a trial on account 
of recommendations, while the inclusion of 21 was due to its time-honoured 
use by fishermen and field naturalists. 
After making due allowance for the variable conditions and divergent 
numbers of mosquitoes present in the cages in the several tests, we suggest 
that our experimental evidence clearly discriminates between the several 
preparations tested; it shows that, while some afford a high degree of pro¬ 
tection, others are of dubious value. 
Without committing ourselves to the conclusion that the value of these 
preparations in the field against Anopheles mosquitoes will be exactly parallel 
to their use against Stegomyia fasciata (Aedes calopus) under laboratory 
conditions, we trust that the work will afford a practicable comparative guide. 
On the other hand we fully appreciate the fact that from the point of view 
of pure science, we have dealt with only the fringe of a large subject, whilst 
as regards the practical issues, a really efficient culicifuge, one that will protect 
continuously for several hours, has yet to be found. 
It is very desirable that further investigation should be made concerning 
the nature of the attraction possessed by man for the female mosquito, and 
the influence exercised by the culicifuge in combating it. 
II. THE CHOICE OF MOSQUITO. 
The choice of Aedes calopus Meigen (= Stegomyia fasciata Fabr., Aedes 
argenteus Poiret) for use in these experiments was due to the possession of a 
West African stock of this species by one of the authors, and by the fact that 
it can be easily reared in captivity. The females are renowned for their 
blood-sucking proclivities, feeding just as readily under laboratory conditions 
as when at liberty, the season of the year making no difference to either 
breeding or feeding, provided that the factors of the temperature and 
humidity are favourable. 
III. METHOD OF REARING THE MOSQUITOES. 
The eggs, laid on strips of filter paper, were immersed in tepid water to 
which was added a small quantity of brewers’ yeast, and placed in an incubator 
at 95° F. to hatch. After hatching they were transferred to another incubator 
kept at 80° F. as the higher temperature was probably responsible for the 
production of weakly adults. 
