How Insects Cause or Carry Disease 51 



stomach they collect in the esophagus and later 

 make their way through the walls of this organ and 

 through the tissues of the body until they at last 

 reach a place along the back just under the skin. 

 Here as they are completing their development 

 they make more or less serious sores on the backs 

 of the infested animals. The hides on such ani- 

 mals are rendered nearly valueless by the holes 

 made by the larvae. When fully mature they drop 

 to the ground and complete their transformations. 



The sheep bot-flies (Fig. 32) lay their eggs in 

 the nostrils of sheep. The larvae pass up into the 

 frontal sinuses where they feed on the mucus, 

 causing great suffering and loss. Many other 

 species of animals are infested with their own par- 

 ticular species of bots. Several instances are 

 recorded where the oxwarble has occurred in man, 

 always causing much suffering and sometimes 

 death. 



One or more species of bot-flies occurring in the 

 tropical parts of America frequently attack man. 

 The early larval stage soon after it has entered the 

 skin is known as the Ver macaque. Later stages 

 as torcel or Berne. The presence of the larvae pro- 

 duces very painful and troublesome sores. It is 

 supposed that the adult flies (one species of which 

 is Dermatobia cyaniventris) lay their eggs on the 



