THE FLIES THAT CAUSE MYIASIS IN MAX 107 



have been due to penetration of the spinal cord. In another case a 

 small boy died after a larva had produced a fetid ulcer around the 

 back teeth of the lower jaw. 



Occasionally first-stage larvae enter the eye. sometimes through 

 the optic nerve. Cases have been recorded in which larvae were found 

 in the eyeball, sometimes in the posterior and sometimes in the an- 

 terior chamber. The larva may usually be removed from the anterior 

 chamber, but in the posterior it is more difficult to reach; it may 

 work beneath the retina and detach that structure. Such parasitism 

 may result in the loss of an eye. Intense pain may be felt, sometimes 

 accompanied by nausea and vomiting. 



Because of the confusion regarding the number of larval stages, 

 it is not always possible to tell from published accounts how far the 

 parasite had progressed in its development. In one case, however, 

 eight out of nine larvae of H. diana removed from a human subject 

 pupated, and two of these developed into adult males. 



Treatment consists in removal of the parasites. If an open warble 

 has been formed, the grubs can be squeezed out by pressure: if not, 

 removal by surgical means may be indicated. To remove the larva 

 from the anterior chamber of the eye. an operation is necessary; larval 

 parasitism of the posterior chamber may necessitate the removal of 

 the eyeball. 



Literature. — For a general account of the life history, biology, 

 and veterinary and medical aspects, including some case histories, see 

 Bishopp. Laake. Brundrett. and Well- (18) ; for taxonomy, in addi- 

 tion to the above, see Patton (107) and Toomey ( 152) : for medical 

 and clinical aspects, see Toomey (153) : for discussions of ophthal- 

 momyiasis, see Anderson (3) and O'Brien and Allen (95). 



KEY TO SPECIES 



ADULTS 



JL Abdomen with reddish-yellow pile at the apex : scutellum with but shallow 



emarginations at the sides or apex 2 



Abdomen with yellowish pile at the apex : scutellum with deep emargi- 

 nations at the apex and the sides, thus appearing as 4-lobed diana Brauer 



2. Scutellum only very indistinctly notched at the apex; first segment of each 

 tarsus slightly longer than the following 3 combined; mesonotum 

 conspicuously reddish-yellow pilose in front, black behind- bovis (Linnaeus) 

 Scutellum slightly, bnt distinctly, notched at the apex: first segment of 

 each tarsus equal to or shorter than the combined length of the following 

 3; mesonotum uniformly yellow-pilose lineatum (Villers) 



LARVAL STAGES U 



Month hooks present: posterior spiracles consisting of simple circular 

 openings stage I 



Mouth hooks rudimentary; posterior spiracles with IS to 40 openings. 

 arranged in squarish or irregular masses and not surrounding a 

 button • stage II 



Mouth hooks rudimentary: posterior spiracles with numerous openings, 

 kidney-shaped, and partially surrounding the button (rig. 55) stage III 



u The characters for differentiating the larvae have been taken from various 

 sources, but chiefly from Laake. However, Natvig (92) has shown that they do 

 not always hold: so they should be used with caution. If exact and positive 

 determination is necessary, it will be best to consult the Laake and Natvig papers. 



