


During its life the fly passes through 
four stages: egg, larva, pupa and adult. 
The eggs are laid by the female in 
filth of some sort — preferably in horse 
manure, but frequently in human excreta. 
The larva or maggot, hatching from 
the egg, feeds upon this substance and 
grows to a length of perhaps half an inch, 
when it burrows down to a dry place and, 
upon casting its skin, becomes a dormant 
pupa. From this pupa the adult fly 
emerges, to wing its way from filth to 
our food. 
As each female lays an average of 
one hundred and twenty eggs, and as nine 
generations are possible in one season, a 
single female may, under ideal conditions, 
be responsible for several hundred trillion 
offspring. 
As a result of its nasty habits, the 
fly is a germ-laden creature. 
If it has access to human discharge 
and then to food the fy may become a 
disease bearer. The fly was largely re- 
sponsible for typhoid fever during the 
Spanish-American War, while it has been 
suspected of causing epidemics in times of 
peace. It has been shown that infants 
in fly-infested houses of New York City 
are visited by two and a half times as 
much summer complaint as those in clean 
homes. 
Such conditions as these demonstrate 
the necessity of ridding ourselves of the 
fly. This is best done by the following 
means: 
a3 
THE FLY 
In a case at the entrance to the Hall 
is a huge model of the House Fly. 
In WALL CASE 11 4 series of four 
jars illustrates the fly’s life cycle, 
while charts give the time required at 
various temperatures for the complete 
transformation and the relative impor- 
tance of various breeding substances. 
A jar on the bottom shelf shows the 
number of flies found breeding in 
a pound of manure. CHART 32 
shows two typical breeding places. 
This fact is illustrated by four jars and 
a picture on the top shelf of WALL 
CASE 11. 
Several culture plates in the same case 
show the bacteria which developed in 
the tracks of a fly, and tubes of sand 
represent the number of bacteria 
washed from flies. CHART 31 shows 
a much enlarged fly foot with disease 
bacteria clinging to it. 
See a model nm WALL CASE 11 
(top shelf, right) and a small map at 
the extreme left. 
A model in the center of the same 
case illustrates this fact. 
For summary see CHART 29. 
