228 



EM A SCUL ATI NG-FLY 



to some a few words about them will not come amiss, though 

 these flies do not injure our domesticated animals. Fig. 184* 

 explains itself. The host is a striped gopher, which harbored 

 three of these bot-flies, two smaller ones and one almost fully 

 grown. The tumors made by the large one and by one 

 of the smaller ones are shown; they are under the skin 

 and each communicates w^ith the outside by means of an 

 opening. Against these openings were pressed the anal ends 

 of the larvae, which contained the breathing-organs. The third 

 larva was found in the neck of the gopher. The old story 

 told by hunters that mature male squirrels are in the habit of 

 emasculating the younger ones, for very selfish reasons, finds 



Fig. 185. — Adult of emasculating-fly. Enlarged. Original. 



thus a more natural explanation. Some years ago the 

 writer observed a fly belonging to the above genus leavings 

 the burro v^ of a striped gopher. Though it is not w^ise to 

 jump to conclusions, we may take it for granted that this fly 

 is the adult of such emasculating bots. It is illustrated in 

 fig. 185. As seen by the line giving the size of the insect it is 

 a large fly, with a black face free from hair, large red eyes, a 

 polished black thorax covered on the sides v^^ith long yellow 

 hairs, the scutellum is covered with short black hairs, the 

 abdomen is polished, of a dark steel-blue color, and sparseh^ 

 covered with short black hair; only the penultimate 



