FLESH FLIES 257 



with negative result, but also allowed flies which had fed on antelopes, which were 

 infective for laboratory animals, to feed on himself, likewise with negative result. It 

 is a well-known fact that men in good condition are refractory to trypanosome infec- 

 tion so that this courageous experiment does not prove the antelope strain to be 

 different from the human one. 



One measure that has been proposed is to kill off the big game from a certain area 

 with a view to depriving the flies of their main source of infection. 



The probabilities of an animal reservoir for T. gambiense however is not so well 

 settled. ^Many think that we may have trypanosome carriers and that such persons 

 in the enjoyment of health may act as reservoirs of the virus. Koch suggested that 

 crocodiles were important factors in the life of the tsetse flies and recommended 

 the destruction of the crocodile eggs. 



Glossina morsitans transmits the cattle trypanosome disease, nagana and the 

 human infection due to Trypanosoma rhodesiense. 



Auchmeromyia luteola. This is an African fly, the larva of which is known as 

 the "Congo floor maggot," and is a blood sucker. The larva is of a dirty-white 

 color and about %j inch long. It crawls out at night and feeds on the sleeping native. 

 This is the only known instance of a blood-sucking larva. 



Calliphora vomitoria and Lucilia caesar. These are flies with brilliant metallic- 

 colored abdomens, commonly called blow flies in the case of Calliphora and blue- 

 bottle flies for Lucilia. They deposit their eggs on tainted meat and in wounds. 

 Many cases of obscure abdominal trouble are probably due to the larvae of these 

 flies. Intestinal myiasis is undoubtedly of greater importance than has been 

 thought. The larvae, with hook-like projections anteriorly and a ringed body, can 

 easily be recognized in the faeces. They have been mistaken for flukes. They 

 also have a tendency to be attracted by those with ozena and the larvae may develop 

 in the nostrils. Cheeks bare in Lucilia, hairy in Calliphora. 



Chrysomyia macellaria. This is known as the screw- worm when in the larval 

 stage. The adult fly resembles the blue-bottle flies. It is distinguished from them, 

 however, by the presence of black stripes on thorax. These flies are very common 

 over nearly all North and South America. The eggs which number 250 or more, 

 when deposited in the nostrils or in wounds, develop into the screw-worm larva, 

 which may, by going up into the frontal sinus, cause death. These larvae have 

 twelve segments with rings of minute spines. 



Ochromyia anthropophaga (Cordylobia anthropophaga or Tumbu Fly). This 

 is an African fly whose larvae develop under the skin of man and animals. It is 

 known as the Ver de Cayor. The larva resembles the Ver Macaque, is rather 

 barrel-shaped and beset with small spines. It bores its way into the skin and makes 

 a lesion like a boil which has a central opening through which the larva breathes. 



Sarcophagidae 



These are known as "flesh flies." The most important characteristic is the fact 

 that the arista is plumose up to the mid-point, beyond which it is bare. They are 

 usually thick set and moderately large flies. 



Sarcophaga carnaria. This is a grayish fly with three stripes on thorax and 

 black spots on each segment of the abdomen. It is viviparous. The larvae gain 

 access to nasal and other cavities and there develop. Cases of death have been 



