224 



THE ABDOMEN AND ITS CONTENTS. 



there unsuspected until it weighed nearly half-a-pound, it then hecame entangled m 

 the pyloric orifice, and prevented the passage of the food, and destroyed the horse.* 



BOTS. 



In the spring and early part of the summer, horses are much troubled by a grub or 

 caterpillar, which crawls out of the anus, fastens itself under the tail, and seems to 

 cause a great deal of itching or uneasiness. Grooms are sometimes alarmed at the 

 appearance of these insects. Their history is curious, and will dispel every fear 

 with regard to them. We are indebted to Mr. Bracy Clark for almost all we know 

 of the bot. 



CUT OF THE BOT. 



o and b The eggs of the gad-fly, adhering to the hair of the horse 



c The appearance of the bots on the stomach, firmly adhering by their hooked moutha. 



The marks or depressions are seen which are left on tiie coat of the stomach 



when the bots are detached from their hold. 

 d The bot detached. 



e The female of the gad-fly, of the horse, prepared to deposit her eggs. 

 / The gad-fly by which the red bots are produced. 

 g The smaller, or red bot. 



A species of gad-fly, e, the cetrus equi, is in the latter part of the summer exceed- 

 ingly busy about the horse. It is observed to be darting with great rapidity towards 

 the knees and sides of the animal. The females are depositing their eggs on the 

 hair, and which adhere to it by means of a glutinous fluid with which thej^ are sur- 

 rounded (a and b). In a few days the eggs are ready to be hatched, and the slight- 

 est application of warmth and moisture will liberate the little aniinals which they 

 contain. The horse in licking himself touches the egg; it hursts, and a small worm 

 escapes, whicli adheres to the tongue, and is conveyed with the food into the stomach. 

 There it clings to the cuticular portion of the stomach, c, by means of a hook on 

 either side of its mouth; and its hold is so firm and so obstinate, tliat it must be 

 broken before it can be detached. It remains there feeding on the mucus of the sto- 

 mach during the whole of the winter, and until the end of the ensuing spring; when, 

 having attained a considerable size, d, and being destined to undersjo a certain trans- 

 formation, it disengages itself from the cuticular coat, is carried in^o the villous por- 

 tion of the stomach with the food, passes out of it with the chyme, and is evacuated 

 with the dung. 



The larva or maggot seeks shelter in the ground, and buries itself there; it con- 

 tracts in size, and becomes a chrysalis or grub, in which slate it lies inactive for a 

 few weeks, and then, bursting from its confinement, assumes the form of a fly. The 

 female, becoming impregnated, quickly deposits her eggs on those parts of the horse 

 which he is most accustomed to lick, and thus the species is perpetuated. 



There are several plain conclusions to be drawn from this history. The bots can 



* The Veterinarian, vol. vii., p. 76. 



