THE FLIES THAT CAUSE MYIASIS IN MAN 95 



accidental hosts include dogs, hyenas, rabbits, and crows. At least 

 two cases are on record of larvae of an unidentified species of Gastero- 

 philus infesting the digestive tract of man and producing distressing 

 symptoms. 



For a case of ophthalmomyiasis see Gasterophilus intestinalis. 



Since the larva generally burrows in the superficial layers of the 

 skin, it may usually be removed by a very simple operation not requir- 

 ing a local anesthetic and without injury to the blood vessels. Ordi- 

 narily it is difficult to locate the larva, which is not always found 

 at the extreme end of the burrow. Austmann (8) used, with complete 

 success. Lombard's method of clearing the epidermis by applying 

 ordinary clear machine oil around the end of the burrow; he then was 

 able to remove the larva with the point of a needle. A discussion of 

 various types of treatment that have been used is given by Austmann. 



Literature. — For important references to parasitism of man by 

 Gasterophilus, see Austmann (5), Seguy [138), and Pavlovsky and 

 Stein (112) ; for an extensive discussion of the biology and immature 

 stages, see Dinulescu (33) ; for a taxonomic treatment, including keys 

 to at least the three species of medical importance and extensive 

 descriptions, see Wells and Knipling (159) (in English) , Seguy (135) 

 (in French), or Paramonov (97) (in Ukrainian). 



KEY TO SPECIES 



ADULTS 



1. Wings clouded with a median band and 2 isolated spots near the apex 



(fig. 4. r >) : lower squama no larger than the upper 1; pile of abdomen 



short and inconspicuous, never bushy intestinalis (Degeer) 



Wings unclouded ; lower squama distinctly larger than the upper 1 ; 

 abdomen in unrubbed specimens with considerable long bushy pile, at 

 least at the base 2 



2. Vein m 3 distant by much more than its length from cross vein r-m 



(fig. 42) haemorrhoidalis (Linnaeus) 



Vein m 3 nearly meeting the cross vein r-m (cf. intestinalis, fig. 45) 



nasal is (Linnaeus) 



THIRD-STAGE LARVAE 



1. Spines on the anterior margins of the segments arranged in a single row 



(fig. 44, A) , nasalis (Linnaeus) 



Spines on the anterior margins of the segments arranged in a double row, 

 those of the front row being the more strongly developed 2 



2. Spines small, tapering to a fine point; spines lacking on at least the 



middle half of the dorsum of segment 10 and on the entire dorsum of 



segment 11 (fig. 44, C) haemorrhoidalis (Linnaeus) 



Spines larger and stronger, blunt at the apices ; only 1 or 2 pairs of spines 

 lacking on the dorsum of segment 10 : segment 11 with 1 to 5 spines 

 above the lateral line on each side (fig. 44, B) intestinalis (Degeer) 



FIRST-STAGE LARVAE 



1. Spines at the anterior margins of the segments in one closely set row ; 



body with some long scattered hairs; hooks on the ventral side of 



segment 2 very long (fig. 43. A) nasalis (Linnaeus) 



Spines at the anterior margins of the segments in 2 rows: body with at 

 most short, inconspicuous hair; hooks on the ventral side of the second 

 segment not especially long, that is. no more prominent than the spines, 2 



2. Larvae straplike, subfuslform (fig. 43, B) intestinalis (Degeer) 



Larvae less elongated, fusiform (fig. 43, C) haemorrhoidalis (Linnaeus) 



