Some of the other recorded cases have not resulted so favorably, for the eyesight has been seriously affected or even lost. According to Edmund and Etienne Sergent (1907), myasis caused by the larvæ of _Oestris ovis_ is very common among the shepherds in Algeria. The natives say that the fly deposits its larvæ quickly, while on the wing, without pause. The greatest pain is caused when these larvæ establish themselves in the nasal cavities. They then produce severe frontal headaches, making sleep impossible. This is accompanied by continuous secretion from the nasal cavities and itching pains in the sinuses. If the larvæ happen to get into the mouth, the throat becomes inflamed, swallowing is painful, and sometimes vomiting results. The diseased condition may last for from three to ten days or in the case of nasal infection, longer, but recovery always follows. The natives remove the larvæ from the eye mechanically by means of a small rag. When the nose is infested, tobacco fumigations are applied, and in case of throat infestation gargles of pepper, onion, or garlic extracts are used. _Rhinœstrus nasalis_, the Russian gad-fly, parasitizes the nasopharyngeal region of the horse. According to Portschinsky, it not infrequently attacks man and then, in all the known cases deposits its larvæ in the eye, only. This is generally done while the person is quiet, but not during sleep. The fly strikes without stopping and deposits its larva instantaneously. Immediately after, the victim experiences lancinating pains which without intermission increase in violence. There is an intense conjunctivitis and if the larvæ are not removed promptly the envelopes of the eye are gradually destroyed and the organ lost. [Illustration: 81. Larvæ of Dermatobia cyaniventris. After Blanchard.] [Illustration: 82. Young larva of Dermatobia cyaniventris. After Surcouf.] _Dermatobia cyaniventris_--This fly (fig. 83) is widely distributed throughout tropical America, and in its larval stage is well known as a parasite of man. The larvæ (figs. 81 and 82) which are known as the "ver macaque," "torcel," "ver moyocuil" or by several other local names, enter the skin and give rise to a boil-like swelling, open at the top, and comparable with the swelling produced by the warble fly larvæ, in cattle. They cause itching and occasional excruciating pain. When mature, nearly an inch in length, they voluntarily leave their host, drop to the ground and complete their development. The adult female is about 12 mm. in length. The face is yellow, the frons black with a grayish bloom; antennæ yellow, the third segment four times as long as the second, the arista pectinate. The thorax is bluish black with grayish bloom; the abdomen depressed, brilliant metallescent blue with violet tinge. The legs are yellowish, the squamæ and wings brownish.