CHAPTER IV. 



ANIMAL PARASITES IN THE STOMACH. 

 HELMINTHIASIS. 



GASTROPHILUS. BOTS. 



Varieties. — The larvae of bot flies occur in the stomach 

 and bowel of the horse. The following varieties have been 

 described: (a) Gastrophilus equi, which is usually found 

 in the esophageal portion of the stomach. (6) Gastrophilus 

 pecorum, found in the "stomach, duodenum and rectum 

 (Hungarian and Russian horses), (c) Gastrophilus hemor- 

 rhoidalis, found in the pyloric portion of the stomach, 

 duodenum, and rectum, (d) Gastrophilus nasalis, found 

 in the pyloric portion of the stomach arid duodenum. 



Life History. — The female botfly, which is common in 

 summer, flying over the pasture fields and roads, deposits 

 her eggs on the skin of the horse, especially on the hairs of 

 the front legs, mane, neck, and about the nose and mouth. 

 In from three to five days there issue from the eggs the 

 larvae, which are licked off by the horse, reach the stomach, 

 where they attach themselves to the mucous membrane, to 

 remain until the following spring. In the months of May 

 to July, and sometimes' during the late summer, the bots 

 leave the stomach, pass into the intestines and are voided 

 with the feces. Either on the ground or in the manure they 

 change into the chrysalis stage. In about one month the 

 mature fly emerges, and after copulation the females deposit 

 their eggs as described. 



The gastrus larvae are found in the stomach of all horses 

 on pasture in small towns or where the botfly appears. 

 Generally speaking, the larvae are harmless. Only in very 

 exceptional cases do they cause illness through traumatic 

 gastritis (symptoms of indigestion, intermittent attacks of 



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