They are very small; they get into the nostrils, and cause animals to become blind by introducing themselves 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, have 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 all 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 military 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
soldier threw up with his spittle more than two hundred larvæ of this fly. We give below the figure of the larva and of the perfect insect. He had found this man sick in Michoacan, at a height of 1,866 metres, between Mexico and Morelia.
Fig. 9.—Lucilia hominivora.
Fig. 10.—Lucilia hominivora, larva.