DIPTERA. “FT 
learned men, but the mention in ancient writings of the Oéstrus and 
its habits is now generally considered as referable to some of the flies 
capable of piercing, such as the gad-flies or horse flies and not the bots. 
The occurrence of two or three similar species affecting the horse has 
led to some confusion in their names. Thus the Gstrus equi of Lin- 
neus appears to correspond with the Gstrus vituli of Fabricius, while 
the Jatter author includes in Mstrus equi the Uistrus nasalis, dvstrus 
hemorrhoidalis, and Gstrus veterinus of Linneeus. Without going into 
a discussion of this synonymy here, it will be seen that all of these 
forms were apparently familiar to scientific writers more than a century 
ago as well as the more striking features of their life history. Thus 
the statement made by Linnzus (Turton’s translation, p. 582) reads as 
follows: ‘‘ Deposits eggs on the hairs of horses, and always on those 
parts which are most liable to be licked by the tongue; these, either 
in the egg or larval state are conveyed by the tongue into the stomach, 
and passing through the intestines with the food are discharged with 
the dung.” These larve are commonly known by the name of bots. In 
1815 Mr. Bracy Clark published his essay on bots of horses and other 
animals presenting the results of thorough investigation upon these 
interesting parasites, and subsequent investigation has but confirmed 
in large part the conclusions reached by him. 
NATURE AND EXTENT OF INJURY. 
Different writers have placed very different estimates upon the 
injury due to bots, and as great diversity, or perhaps greater, exists in 
the opinions of practical men and veterinarians, some holding that the 
presence of the bot in the horse’s stomach does not interfere with its 
normal activities, while others look upon them as extremely dangerous 
and sometimes refer almost any serious disturbance of the digestive 
organs, or death from unknown cause, to bots. 
The injury to the horse from the larve may take four forms: (1) The 
attachment to the walls of the stomach causes an irritation which may 
interfere with the normal action of the glands or reduce the extent of 
glandular surface; (2) the bots abstract some nutriment from the 
walls of the stomach, or by absorption, from the contents of the stom- 
ach itself; (3) by collecting, particularly in the region of the pylorus, 
they serve as an obstruction to the free passage of food from the stom- 
ach to intestines; (4) in passage through intestines they may attach 
themselves at times to walls or in rectum and cause great irritation. 
Some consider this as the source of most of the serious symptoms from 
presence of bots. In any of these methods the extent of injury depends 
in large degree upon the number of bots present, a few probably caus- 
ing no appreciable damage, while large numbers (sufficient, as we have 
seen them, to completely cover large patches of the stomach walls) 
must cause serious disturbance and loss of nutrition and would seem a 
sufficient cause to produce fatal results, From the nature of the case 
