FLIES 223 



worms of birds and disseminate them far and wide. Moreover they 

 carry a truly remarkable number of bacteria about with them. Pains- 

 taking Chinese workers calculated the grand total from a single house- 

 fly and found 3,500,000 adhering to the outside and 30,000,000 to the 

 inside of its body. 



Parasitic larva of bot-fly, Hypoderma bovis, (x 3 . 5) 



