DIPTEROUS LARV^ 57 



Gasteophilus Hemorrhoidalis 



The red-tailed botfly. — CEstridse (p. 53). Somewhat smaller than 

 G. intestinalis. Dark brown color, yellowish hairs upon the face; trans- 

 verse black band upon thorax. The abdomen is covered with fine hairs 

 which in the middle are dark and posteriorly orange-red. The wings are 

 clear. 



This species of horse botfly is foimd in common with G. intestinalis in 

 North America and Europe. 



The females attach their ova to the hairs of the horse, preferably 

 those about the hps. The hatched larvae cause an irritation which 

 impels the horse to pass its tongue about its lips, thus carrying the 

 parasite into the mouth. In other respects its life history is essentially 

 the same as that of G. intestinalis. The larvae differ from those of the 

 latter in being somewhat smaller and in their dark-red color. There is 

 also some difference in their habitat in that they attach usually to the 

 pyloric portion of the stomach, and when fully developed pass on to the 

 rectum where they remain for some time, assuming a green color before 

 being voided. 



Effect. — The presence of the larvae of this fly in considerable num- 

 bers in the folds of the rectal mucous membrane may cause an annoying 

 irritation, inducing violent efforts at defecation. Such cases, however, 

 are extremely rare, and, as a rule, little or no evidence is given by the 

 animal of their presence. 



Gastrophilus nasalis. — CEstridae (p. 53). This species, commonly 

 called the chin fly, is about 1 cm. (^/s of an inch) in length. The body is 

 hairy and j'ellowish red in color. The wings are without spots. 



Law describes the larvae as "furnished with a row of spines on each 

 ring from the second to the ninth on the dorsal surface, and as far as the 

 tenth on the ventral. There is an unarmed part in the center of the 

 eighth and ninth rings on the dorsal surface." 



The fly deposits its eggs about the lips and nostrils. The larvae attach 

 to the mucosa of the upper part of the small intestine. 



Fitch states (1918), as to New York State, that from examination of 

 the larvae it would seem that Gastrophilus nasalis is quite as frequent 

 as G. intestinalis. 



Htpoderma Lineata and H. Bovis 



The ox botflies; warble flies (Fig. 29). — (Estridae (p. 53). Hypoderma 

 lineata is about five-eights of an inch in length. The general color is 

 black; body more or less covered with hairs. The front, sides, and back 

 of the head, sides of thorax, and last segment of the abdomen are covered 

 with long yellowish white hairs. 



This fly is found in all parts of the United States, but more especially 



