No. 4.] Reprints 222 



3. REPRINTS. 

 I. THE HORSE BOT-FLIES. 1 

 Gastrophilus equi^ Fabr. 



Bots in horses have been a familiar form of parasite to farmers, 

 stockmen, and veterinarians for we know not how long. Whether 

 they were familiar to the ancients has been a matter of discussion 

 among learned men, but the mention in ancient writings of the 

 CEstrus 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 CEstrus equi of Linnaeus appears to correspond with the 

 CEstrus vituli of Fabricius, while the latter author includes in 

 CEstrus equi the CEstrus nasalis, CEstrus hsemorrhoidalis, and 

 CEstrus veterinus of Linnaeus. 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 Linnaeus (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 dis- 

 charged with the dung." These larvise are commonly known by the 

 name of bots. In 18 15 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 in- 

 vestigation 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. 



^ Extracts from a report by Herbert Osborn, published in Bulletin No. 5, United 

 States, Department of Agriculture, Division of Entomology, 1896. 



