GASTROPHILUS HAEMORRHOIDALIS AND OTHER BOTS. 13 



the stomach. He mentions cases of perforations, lacerations, and 

 ruptures of the stomach observed by Flohill, Numan, Conti, and 

 Brusasco, and calls attention to alveolar lesions which are naturally 

 more predisposed to induce various infective diseases. ( See Plate II. ) 



GASTROPHILUS AND SWAMP FEVER. 



Aside from the lesions which may induce the entrance of organisms 

 of infectious diseases, the Seyderhelms, of Strassburg (1914), report 

 results which they think implicate Gastrophilus larvae in the causa- 

 tion of swamp fever. It is believed by them that the larva? excrete 

 a specific toxin which is the cause of the disease, for by administer- 

 ing extracts of these larvae symptoms typical of swamp fever have 

 been observed. The coincidental distribution of Gastrophilus with 

 that of this disease would appear to bear out the hypothesis. It is 

 said that the most virulent reactions were obtained in these experi- 

 ments with G. haemorrhoidalis larvae. 



BOT-FLY ANNOYANCE. 



In those portions of the country where the nose-fly does not occur, 

 horses are seldom sufficiently annoyed to require protection. The 

 persistence of the common bot-fly and the repeated stamping of the 

 animals are evidence that it is annoying, but when the throat bot- 

 fly " strikes " the action of the horse becomes more violent. 



The throat bot-fly is less persistent but more determined in de- 

 positing, and the horse usually responds with a violent nod or jerk, 

 the violence depending upon the nervousness of the individual. In 

 plowing it is sometimes necessary to place a strip of cloth or a small 

 branch of a tree underneath the throat latch and extending to the bit 

 rings. 



In the nose-fly section the annoyance is produced by the two gener- 

 ally distributed species in addition to G. haemorrhoidalis. Upon the 

 approach of this fly the horse moves the head backward and forward 

 to prevent its darting on the lips, but this only seems to arouse its 

 determination, for it quickly alights on the lips and within a second 

 or two deposits a black egg. It apparently occasions a most annoy- 

 ing sensation, and a horse will most often snort and rub violently 

 against the ground, a bowlder, a tree, barb- wire fence, or any con- 

 venient object. 



The effects of ovipositions on pastured animals are worry, loss of 

 flesh, and mechanical injuries. If the lips are examined barb-wire 

 lesions will be found which resulted from the rubbing of the horse 

 following an oviposition. (See Plate IV.) 



With an unprotected work animal one may be suddenly confronted 

 with a jerk or a similar violent action of the animal at each oviposi- 

 tion of the fly. When a few eggs have been deposited the animal 



