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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
starch, together with a solution of proteins or products of protein 
hydrolysis. These materials may be given in the form of lump sucrose 
dropped into the breeding jar or semi-liquid starch paste dropped on the 
cover.- This must be supplemented with nutrient bouillon, blood serum 
or egg white. Milk alone is also an efficient food on account of the fact 
that it contains the two factors mentioned in the form of lactose and 
casein. 
On the foods mentioned the longevity of the adult M. domestica varies 
from 2 to 57 days, with an arithmetical mean of 20 + days. During 
this time the ovaries and testes develop and eggs are deposited in from 
11 to 24 days with an arithmetical mean of 15 days. 
The sex ratios of all the cultures, whether from first generation 
flies obtained from wild females or from inbred material, showed certain 
slight variations, but in general the sexes are equal numerically. An 
effect on the sex ratio, that could be directly and safely attributed to 
climatic conditions or to a special type of food was not obtained. 
Stomoxys calcitrans L. 
The biting stable flies have been reared by the writer from April 22 
to December 7. After this time the cultures automatically “died out” 
as with the house flies. 
Fermenting oat straw alone, horse manure alone, and a mixture of 
the two were extensively used for a larval medium. As a matter of 
routine, pure horse manure was finally adopted as the best and most 
practical medium. The cultures are prepared in the manner described 
for M. domestica. 
The life history of Stomoxys calcitrans has been very fully and ac¬ 
curately described by Newstead (3) in 1906, and by Bishopp (4, 5) in 
1913 and 1920. It is very similar to that of the house fly. If wild gravid 
females are put in the breeding jars, they soon lay their eggs which hatch 
in from 1 to 3 days. According to Bishopp larval development takes 
11 to 30 days or more, and the metamorphosis within the pupal case 
6 to 20 days or longer depending on the temperature. Bishopp obtained 
18 days as the minimum time and 53 or more days as the maximum time 
required for development from egg to adult. 
The writer has noticed a somewhat greater effect of temperature on 
the rapidity of development in Stomoxys than in house flies. During 
very hot weather the cycle from egg to adult may be spanned in as short 
a time as 14 days, whereas cool spring or autumn days may prolong the 
period to 43 or more days. 
To obtain the development of the ovaries and testes of bred Stomoxys , 
