INTRODUCTION | 1] 
those dying from other causes, and the adults of larvae origin- 
ating from infected -carcasses may be positive for the disease. 
Enteric Diseases. <A list of enteric infections spread by blow- 
flies is nearly identical to that of the common housefly and is 
too extensive to be given here. In the slum districts of Pieping, 
China, Yao, Yuan, and Huie (1929) found the common blowflies 
(Calliphora spp. and Lucilia spp.) to earry over 3,500,000 bac- 
teria per specimen. Even in the cleanest and most sanitated 
portions of that city each adult blowfly carried an average of 
nearly 2,000,000 such bacteria. From eight to ten times as many 
bacteria were found to occur inside such flies as on the outside. 
Bacillus coli and B. dysenteriae were the most important of the 
more abundant pathogenic forms found. By washing captured 
blowflies these investigators found Entamoeba coli and cysts of 
certain flagellates and ciliates. Examinations of the digestive 
tract of these flies revealed the presence of all of the above named 
organisms and Endolimax nana as well. Of particular signifi- 
cance was the fact that the death rate from gastrointestinal 
diseases in the areas concerned was roughly proportional to the 
number of blowflies captured. Trophozoites of Hntamoeba histo- 
lytica may be cultivated from the vomit of blowflies from 5 to 17 
minutes after infected..substances are ingested, according to 
Pipkin (1942). He found that cysts of histolytica could be 
retained within the intestinal tract of such flies for from 86 to 
258 minutes and that these could be deposited in a viable state 
in the defecation of the flies. Frye and Meleney (1932) found 
cysts of this amoeba in the intestinal tract of flies captured in 
three of twelve homes in-which infected individuals resided. The 
vibrios of cholera (Vibrio comma) will survive in the intestinal 
tract of blowflies for 24 hours according to Gill and Lal (1931). 
These authors found that vibrios disappear from the body of 
the flies after about 4 hours but reappear on or about the fifth 
day at which time the fly is capable of infecting food by its 
feces. Apparently these flies are not only mechanical vectors 
but may be involved in biological transmission of the disease 
as well. Infected blowflies are able to contaminate food or water 
by the deposition of these vibrios for a period as long as 24 
hours via vomit-drop methods. Meats, fish, and vegetables are 
favorite sources of food for these flies and when eaten uncooked, 
are potential sources of this disease. 
The exact role held by various species of blowflies in the trans- 
mission of virus diseases such as poliomyelitis is not yet clear. 
Virus of poliomyelitis has been demonstrated in stools of in- 
fected persons. This virus has been found to be present also on 
