MYIASIS AND THE (ESTRID& 29 



the section to which the generic term Cephalomyia is 

 given in some books ; species of this section attack 

 deer and other animals. 



The section termed Hypodermince comprises the 

 "worble" flies or "marble" flies. One may imagine 

 that the latter name indicates in the mind of the cow- 

 herd the appearance of the round pustulent boils on 

 the hide of the suffering animal, and that the former 

 name is a corruption of "worm-hole," originating with 

 the tanner, observant of the deterioration of injured 

 hides. A mixing of the terms worm-hole and marble 

 probably originated the name " warble." The maggots 

 live under the skin on the back of oxen, and breathe 

 externally through openings in the boil-like excrescences. 

 The discoloured flesh of infected oxen is called 

 " flecked." Two species of worble-flies are prevalent, 

 one or the other, in many parts of England. 



The third section, to which the sub-family termed 

 Gastrophilina is sometimes applied, comprises the 

 "bot-fly," which commonly infects the horse ; it is the 

 imperfect knowledge of this latter which has led to 

 erroneous surmises explanatory of the horribly dis- 

 gusting fact of human intestinal myiasis. 



All the species of all the three sections are single- 

 brooded. Although the flies themselves can inflict no 

 immediate pain, at their mere sight all the animals out 

 at grass on the farm are seized with an instinctive 

 terror, conspicuously greater than when attacked and 

 copiously bled by any " blinden " breeze flies, which, 

 however, fly more silently and settle on their victims 

 very furtively. One can understand the violent efforts 

 of the horse to free himself from the exceedingly 



