OestridcB, or Bot-flies 



IIS 



Rhincestrus nasalis, the Russian gad-fly, parasitizes the naso- 

 pharyngeal region of the horse. According to Portschinsky, it not . 



infrequently attacks man 

 and then, in all the known 

 cases deposits its larvae 

 in the eye, only. This 

 is generally done while 

 the person is quiet, but 

 not during sleep. The 

 fly strikes without stop- 

 ping and deposits its larva 

 instantaneously. Imme- 

 diately after, the victim 

 experiences lancinating 

 pains which without in- 

 termission increase in 

 violence. There is an in- 

 tense conjunctivitis and 



81. 



Larvas of Dermatobia cyaniventris. 

 chard. 



After Blan- 



if the larvae are not removed promptly the envelopes 

 ot the eye are gradually destroyed and the organ 

 lost. 



Dermatobia cyaniventris — This fly (fig. 83) is widely 

 <iistributed throughout tropical America, and in its 

 larval stage is well known as a parasite of man. The 

 larvse (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 swell- 

 ing produced by the warble fly larvae, 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; antennae 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 squamae and 

 ■wings brownish. 



82. Young larva of 

 Dermatobia cy- 

 aniventris. 

 After Surcouf. 



