A. Bacot and Gr. Talbot 223 
The food given to the larvae—brewers’ yeast, pressed out of its wort—was 
chosen because it gave excellent results in speedy growth; further it was thought 
that there would be less danger of a poisoned bite occurring if a known organism 
were present in excess, than would be the case if a nutrient substance were 
added to the water, and the growth of organisms left to chance. 
The only precaution needed with this food was to adjust the quantity of 
yeast to that of the water and number of larvae present. If too much is added, 
bacteria multiply to such an extent that a scum is produced on the surface, 
and is followed by the death of the larvae. The appearance of any scum on 
the water in the breeding jars should be a signal for a change of water, carried 
out as follows: The water is strained off through a piece of thin cotton or fine 
muslin, the jar refilled with fresh water of about the same temperature, and 
the muslin inverted in it. 
For rapidity of rearing it was found more convenient to segregate the 
pupae and allow the adults to emerge in the incubator at 95° F. than to place 
the jar containing the pupae in the experimental cage. In order to transfer 
the adults quickly, a waxed card cream jar, its bottom replaced by gauze, 
was inverted over the jars containing the pupae, security from falling or 
slipping off being obtained by a ring of stout paper tied round the neck of the 
jar, and projecting beyond its edge. The mosquitoes, as they emerged, ascended 
to the card receptacle. Each morning the stiff paper ring was removed and 
two pieces of card slipped across the top of the glass jar; the upper card was 
lifted and placed, with the receptacle containing the adult insects, on a piece 
of glass, the card withdrawn and the receptacle inverted for the purpose of 
counting the insects before transference to the experimental cage. This is 
effected by inserting receptacle and glass through a sleeve attached to a 
side of the cage (see description in section VII), removing the glass, and tapping 
smartly the sides of the receptacle to make the mosquitoes fly out. 
An equal number of both sexes was transferred to the cages, but by 
dividing the pupae captured each day between the two jars allotted for the 
emergence of adults for each cage, the number of females transferred to each 
can be approximately adjusted. 
Further details in regard to the breeding and bionomics of this species of 
mosquito can be obtained by reference to the report of the Yellow Fever 
Commission, vol. hi (1916). 
IV. CONDITIONS NECESSARY TO MAINTAINING A STOCK OF MOSQUITOES. 
Our first attempts at keeping a large stock of Stegomyia in the cages was 
not very successful owing to the heavy death-rate, due presumably to the 
dryness of the atmosphere, and to the numbers which fell into the water 
receptacles and were drowned. As it was evident that a much more humid 
atmosphere was required, the top of the cages and three of the sides, which 
were of gauze, were covered with waterproof paper. 
Parasitology xi 
15 
