LIFE HISTORY 
berg).* In 1873. Dr. A. S. Packard (1874), then of 
Salem, Mass., studied the transformations of the in¬ 
sect and gave descriptions of all the stages, showing 
that the growth of a generation from the egg to the 
adult state occupies from ten to fourteen days. In 
1895, the writer traced the fly’s life history, discover¬ 
ing that 120 eggs are laid by a single female at a time 
and that in Washington in midsummer a generation is 
produced in ten days. 
Substances in Which This Fly Passes Its Early Life 
It is safe to say that the typhoid fly will breed in 
almost any fermenting organic matter, and it is also 
probably safe to say that if given its preference it will 
lay its eggs on a pile of horse manure. The writer 
once estimated that under ordinary city and town con¬ 
ditions more than ninety per cent, of the flies present 
in houses have come from horse stables or their vi¬ 
cinity, and he is still inclined to think that this esti¬ 
mate is probably correct. But the eggs will also be 
laid upon the excreta of almost any animal. Cow 
manure drying rapidly in a dry season and forming a 
hardened caked surface is not a favorable nidus, yet this 
fly is reared from cow manure at times. Many other 
species of flies prefer cow manure, and a long list of 
*The best of these old papers is little known. It was published 
at Nurenberg in 1764, and is entitled “Geschichte der gemeinen 
Stubenfliege, Herausgeben von J. C. Keller” and covers thirty- 
four pages of text and four plates. The real author is said by 
Hagen to be Freiherr Friedrich Wilhelm von Gleichen (genannt 
Russworm). 
