HORSE FLIES AND CHIGOE. 



71 



For example, a larva of Attacus which was attacked by the 

 Exorista, measured more than four inches in length, was a full 

 inch in diameter, and weighed two ounces. Its body was entirely 

 covered with the empty egg-shells of the fly, the larvae having 

 burrowed into its body. It died, rotted, and in about twelve 

 days there appeared a vast number of maggots very much like 

 those of the blue-fly. They went into the earth at once, and 

 remained in the larval state all the winter. At the beginning 

 of April they changed to pupae, and at the end of May emerged 

 in the perfect state. For the Cecropia Moth see p. 670. 



The curious family of the Hippoboscidae, or Horse Flies, is 

 here represented by an African species which infests the camel. 

 We are all familiar with the Eng- 

 lish Horse Flies, which cling so 

 tightly to the animal with their 

 powerful legs, and run so actively 

 in any direction if disturbed. These 

 insects are remarkable for their 

 manner of reproduction. They do 

 not lay eggs after the fashion of 

 most insects, nor deposit living 

 larvae as do several flies. But the 

 female deposits the pupa ready 

 formed, and enclosed within a soft, 

 white, oval case. Exposure to the 

 air soon hardens this case and 

 turns it brown, and the fly, when 

 developed, makes its escape by 

 pushing off one end of the case. 



-Hippobosca eamelina. 



(Brown.) 



The true position of the Aphaniptera, or Fleas, is still a 

 problem. Systematic entomologists of the present day seem to 

 think that they are least out of place at the end of the Diptera. 



From these I have selected the best-known foreign Flea, the 

 Chigoe {Tulex 'penetrans). This insect burrows into the feet of 

 human beings, and, if left undisturbed, forms a globular hollow 

 in which the young are reproduced. Many accounts of this 

 insect have been published, but I give a short and graphic 

 description by one of my brothers. 



3 D 2 



