14 THE DISEASES OF HOUSES, 



to the horse, and in some cases, as when savin, tobacco, and other power- 

 ful drugs are resorted to, highly dangerous. 



Tbis will bo better understood and appreciated if we give a short sketch 

 of the history of the species of gadfly ((Estrus equi) of which the 

 bot is the grub or larva. In the latter part of summer these flies 

 may be observed very busy about the horses out at grass. The 

 femalo fly darts about the foreparts of the horse, poises herself 

 in the air, and prepares to deposit an egg on the selected part. This 

 is done with great quickness, the egg being left on a hair, to which it is 

 secured by a glutinous liquor which soon dries. The operation is repeated 

 again and again, and on one horse there will sometimes be deposited 

 from four to five hundred of these eggs. Those parts only of the horse 

 are chosen that can be easily reached with his tongue, the insides of 

 the knees, points and sides of shoulders, being commonly selected. 

 The eggs are hatched, or ripe for hatching, in a few days, and as the 

 horse licks himself, which he is the more inclined to do from the teazing of 

 the flies, his warm, moist tongue opens the egg, and liberates a small, 

 lively worm, which gets carried with the food into the stomach, if for- 

 tunate enough to escape the grinders — for, of course, numbers must perish 

 this way. On reaching the stomach they attach themselves by means of 

 two little hooks or tentacles with which they are provided, one on each 

 side of the mouth, to the white coat of the stomach ; here they remain 

 in clusters, firmly fixed, feeding on the mucus of the stomach during the 

 autumn, winter, and spring months. In the early or middle part of summer 

 they voluntarily leave their stronghold, and are discovered by the groom 

 or attendant in considerable numbers as they pass with the dung. They 

 now assume the chrysalis state, and, circumstances being favourable to 

 their development, in four or five weeks each becomes a perfect fly. These 

 mate together, the females deposit their eggs, and so the same wonderful 

 round of changes go on, and the species is perpetuated. 



It will be seen from this that no horse that had not been out at grass 

 the previous summer will have the bots. To this there may be a few rare 

 exceptions, as the gadfly might find the horse in the stable or the fold, or 

 the horse might lick the eggs off a companion brought in from grass. 

 It is generally, if not universally, held by those best capable of forming 

 an opinion on the subject, that bots are harmless to the horse. It 

 is also agreed that it is impossible, by worm medicines, to dislodge them 

 from their hold on the stomach ; for, as has been truly observed, you 

 may push poison down the horse's throat, but you cannot compel the worms 

 to take it, and, therefore, we ought not to torture the horse and risk 

 injuring his constitution by vain attempts at the useless and the impossible. 



Break Down. — There has been considerable difference of opinion as 

 to what constitutes break down, and a good deal of confusion still 

 exists in many minds ; severe sprain of the back sinews being called by 

 many horsey men, and also by numbers of professional writers, break 

 down. But by the more recent writers on these subjects the term is no*r 



