326 



APPLIED ENTOMOLOGY 



Thus far no cure for the disease has been discovered but protection 

 while in Tsetse districts can be obtained by screens, veils, gloves, etc., 

 and by keeping away from the localities in these districts where the flies 

 occur. Its importance is indicated by the estimate that in 10 years 

 between four and five hundred thousand natives died from this disease. 

 Another species of trypanosome carried by Glossina flies causes the 

 disease of domestic animals, particularly hoi'ses and dogs, known as 

 Nagana. This is almost always fatal to these animals. 



Family Sarcophagidae (The Flesh Flies, Fig. 345). — This is a large 

 family of flies, some of which lay their eggs on dead animals. Others 



breed in manure, decaying matter 

 and similar materials, and because 

 of these habits, there is always the 

 possibility of their becoming car- 

 riers of disease-producing germs, 

 though as they seldom visit human 



Fig. 345. Fi"- 346. 



Fig. 345. — Adult Sarcophagid Fly {Sarco-phaga t>p.), much enlarged. {From U. S. 

 D. A. Farm. Bull. 857.) 



Fig. 346. — Adult Tachinid Fly (Tachina mella Walk.), over three times natural size. 

 {From Britton, Tenth Rept. Ent. Conn. Agr. Exp. Sta. 1910.) 



food in houses, the chance that this may result in disease is much less 

 likely than in the case of the house-flies. 



Family Tachinidse (The Tachina Flies). — This family has by some 

 students of the subject been regarded as the most useful family of insects 

 from an economic standpoint, its larvae being parasitic on other insects 

 and being very abundant. This estimate of their importance is probably 

 too high but the group is certainly very valuable in the control of injurious 

 forms. The adults (Fig. 346) somewhat resemble the Muscidse, but the 

 abdomen is liable to be stouter and in many cases bears numerous stiff 

 bristles which arc very noticeable. The eggs (or larvse in some cases) 



