BOTS. 395 



The following are the more frequent kinds of bots : — 



1. The most common form is produced from a gadfly (gastrophilus 

 equi) which lays light, orange-coloured eggs, about the twentieth 

 of an inch in diameter, chiefly on the breast, front of the fore- 

 arms, and those parts of the shoulders and sides that are in reach 

 of the horse's tongue. The eggs are firmly attached to the ends 

 of the hairs of the coat, by a sticky fluid secreted by the fly. The 

 bots, which are about four-fifths of an inch in length, select for 

 preference, as a residence, the Ifeft compartment of the stomach, 

 in which they may be found in scores, and sometimes even in 

 hundreds. 



2. The gastrophilus hcemorrhoidalis lays its eggs on the muzzle 

 of the horse, which it appears to frighten by its approach. The 

 eggs are about the same size as those of the first variety, but are 

 darker in colour, and the bots are smaller in size ; being about five- 

 eighths of an inch in length. Although the left compartment of the 

 stomach is their usual place of first temporary residence, they may 

 attach themselves to the mucous membrane of the passage between 

 the mouth and the respective openings of the gullet and windpipe. 

 They may also be met with in the right compartment of the 

 stomach and in the small intestine close to the stomach. Having 

 remained some months in their selected sites, they become de- 

 tached, and on reaching the lower portion of the rectum, fix them- 

 selves for some time to the mucous membrane of that part. When 

 in this position, they often become exposed to view, on the horse 

 straining when dunging. They are then of a green colour. 



3. Gastrophilus nasaHis lays its eggs, which are white in 

 colour, on the lips and nostrils of the horse. These bots are of a 

 light yellow colour and locate themselves in the small intestine 

 close to the stomach. When full size, they are about three-fifths 

 of an inch in length. Their presence in the intestine is apt to give 

 rise to colic. 



4. Gastrophilus pecorwm is frequently to be found in Eastern 

 Europe. Its eggs and bots closely resemble those of the g. hoemor- 

 rhoidcdis in appearance and behaviour, except that its bots are 

 red. They also attach themselves to the lower portion of the 

 rectum before being finally expelled. 



EFFECTS OF BOTS ON THE HEALTH OF THE HORSE.^Al- 

 though the fact of bots being inside a horse can be of no possible 

 advantage to him ; their presence, when in small numbers, is, as a 

 rule, productive of little or no ill consequence to their host. If 

 their number be large, they cannot help being a source of debility 

 and irritation. In more or less exceptional cases, they cause, espe- 

 cially among young horses, indigestion, loss of condition, and even 



