152 THE COMMON HOUSE-FLY. 
vigilant in the use of fly-screens, fly-traps, etc. During the 
late war the late Professor Leidy pointed out, with bene- 
ficent results, that the common house-fly was instrumental 
in spreading the contagion of hospital gangrene. Why not 
beware of this imprudent and ubiquitous little dipter in car- 
rying and spreading the contagion of the dreaded Asiatic 
plague now menacing us?”’ 
“During the months of August, September and October, 
but mainly during September, it is a very common occur- 

Fig. 127.—Disease of house-fly. Greatly enlarged. 
rence to find dead house-flies adhering to the walls, window- _ 
panes and other conductors of heat, firmly fixed by their 
proboscis and with the legs spread outin quite an unnatural 
manner, thus differing from dead flies in general which have 
the legs contracted. In about twenty-four hours after death 
a kind of fatty substance of a white color is found in the 
form of a ring projecting out between each of the rings of the 
