136 DIRECT INJURIES CAUSED BY INSECTS, 



devourers of man than the Diptera) and these are chiefly 

 to be found in the numerous tribe of the Muscidce. The 

 Gad-fly {(Estrus^L.) you have, doubtless, often heard of, 

 and how sorely it annoys our cattle and other quadru- 

 peds; but I suspect have no notion that there is a species 

 appropriated to man. The existence, indeed, of this species 

 seems to have been overlooked by entomologists (though 

 it stands in Gmelin's edition of the Systema NaturtE*) 

 upon the authority of the younger Linne,) till Humboldt 

 and Bonpland mentioned it again. Speaking of the low 

 regions of the torrid zone, where the air is filled with 

 those myriads of mosquitos which render uninhabitable a 

 great and beautiful portion of the globe, they observe that 

 to these may be joined the CEslrus Hominis, which de- 

 posits its eggs in the skin of man, causing there painful 

 tumours b . Gmelin says that it remains beneath the skin 

 of the abdomen six months, penetrating deeper, if it be 

 disturbed, and becoming so dangerous as sometimes to 

 occasion death. The imago he describes as being of a 

 brown colour, and about the size of the common house- 

 fly; so that it is a small species compared with the rest of 

 the genus. Even the gad-fly of the ox, leaving its 

 proper food, has been known to oviposit in the jaw of a 

 woman, and the bots produced from the eggs finally 

 caused her death c . — Other flies also of various kinds thus 

 penetrate into us, either preying upon our flesh, or get- 

 ting into our intestines. Leeuwenhoek mentions the case 

 of a woman whose leg had been enlarging with glandular 

 bodies for some years. Her surgeon gave him one that 



a From Pallas N. Nord. Beytr. i. 157. 

 b Essaisur la Geograph. des Plantes, 136. 

 c Clark in Linn, Trans, iii. 323, note. 



