PARASITES FREE DURING THEIR WHOLE LIFE. 119 



Besides the gnats, which belong to the family of 

 Cidicidse, there are also the Ceratopogon, and especially 

 the Sim^diuni molestum, known in North America under 

 the name of Black-flies: "the tormenting black-flies of 

 this country," as the Americans say. Certain Nemocera, 

 known by the name of Illiagio, put to flight both man 

 and animals. 



They are very small ; they get into the nostrils, and 

 cause animals to become blind by introducing them- 

 selves into their eyes. In addition to these hurtful 

 insects, we find others fatal to the life of animals, and 

 which are a real plague in certain countries. 



The numerous travellers who have explored the 

 interior of Africa, laave almost all spoken to us. of a fly 

 which attacks beasts of burden, and kills them in a few 

 hours; this is the Tsetse (Glossina morsitans) . More 

 than one expedition has failed on account of this 

 dipterous fly. It was this which obliged Green to 

 abandon his plan of reaching Libebe, by causing him 

 to lose one after another aU his beasts of burden and of 

 draught. The horse, the ox, and the dog are more 

 especially attacked by this terrible fly between the 22nd 

 and 28th degree of longitude, and the 18th and 24th of 

 south latitude. Happily it does not produce any effect 

 upon man. 



There is another fly in Mexico which is dangerous to 

 man ; it is known by the name of Musca hominivora, or 

 more correctly, Lucilia hominivora, Vercammer, a mili- 

 tary surgeon of the Belgian army, relates that a soldier 

 in Mexico had his glottis destroyed, and the sides and 

 the roof of his mouth rendered ragged and torn, as if a 

 cutting punch had been driven into those organs. This 



7 



