THE HORSE GAD-FLY. 42I 



back of the animal more than a few seconds. — The 

 Jarvas of this insect are known among the common 

 people by the name of Wornuls, Wormuls, Warbles, 

 or Bots *. 



THE HORSE GAD-FLY f. 



The larva? of this fly are those odd-looking grubs 

 which are commonly found in the stomach of horses, 

 and sometimes, though much less frequently, in 

 the intestines. Here they hang in clusters of from 

 half a dozen to more than a hundred, adhering to 

 the inner membrane of the stomach, by means of 

 two small hooks or tentacula at their heads, whose 

 points turn outward. 



When they are removed from the stomach, they 

 will attach themselves to any loose membrane, even 

 to the skin of the hand. To do this they draw back 

 their hooks, which have a joint near their base, al- 

 most entirely within their skin, till the two points 

 come close to each other; then, keeping them 

 parallel, they pierce through the membrane, and 

 immediately afterwards expand in a lateral direc- 

 tion, and by these means they become perfecly 

 fixed. 



Their food is probably the chyle, that white juice 

 which is formed in the stomach by the digestion of 

 the food, and which is afterwards converted into 



* Lin. Tran. iii. 29 1. tab. 23. 

 t Synonyms,— Oestrus equi. Linn. — Forest-fly, in Hampshire. 



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