TJ. S. DEPARTMENT OF AGRICULTURE. 



to meet the great demand for army horses. Within the nose-fly dis- 

 trict is to be found one of the largest horse-sale points in the world. 



BRIEF LIFE HISTORY OF GASTROPHILUS. 



Our knowledge of the life histories and habits of these insect 

 pests, which is always essential to successful control, is confined for 

 the most part to the classical accounts of Bracy Clark in 1797 and 

 subsequently, although later writers have added important details. 



When the female of Gastrophilus intestinalis (G. equi) becomes 

 sexually mature it is most often observed hovering near' the inside 

 of the knee of a horse, where by preference the eggs are deposited. 

 After a few days, when the larvse develop within the eggs, the horse 

 by scratching the forelegs with the teeth provides sufficient moisture 

 and friction to remove the operculum or small cap of the eggs and 

 inadvertently the larvae are taken within the mouth. The empty 

 eggshells remain attached to the hairs of the legs, whereas the 

 larvse are carried with the food or water to the stomach, where 

 attachment to the stomach walls takes place. Here they undergo 

 development during the autumn, winter, and spring months, and 

 later are passed from the horse with the manure. At this stage pupa- 

 tion ensues and adult flies are produced. 



The other species of bots also spend similar larval periods in the 

 animal, but have habits peculiar to the particular species. 



HISTORICAL. 



The literature containing historical references to the Oestridae 

 carries one to a most remote time. The ancient Greeks and the 

 Latins refer to " an unspeakable fright of cattle," though later 

 writers are not agreed as to whether it was produced by an oestrid 

 or a tabanid. It is certain, however, that Aristotle knew the forms 

 found in the throats of deer. 



The Greek veterinarians Theomnestus and Absyrtus give us the 

 earliest record which could be referred to Gastrophilus when they 

 write of the " biting worms which fix themselves to the anus of the 

 horse," In order to destroy them it was recommended that they 

 be torn from the anus with the fingers and covered with hot ashes 

 and pulverized salt. 



Malpighi in 1697 gave the first description of a gastrophilid larva 

 taken from the stomach of an ass. According to Joly, it belonged to 

 the species G. intestinalis De Geer, while to Brauer it was G. flavipes 

 Olivier. Gaspari published an erroneous opinion that G. haemorrho- 

 idalis deposited its eggs in the rectum of the horse during def- 

 ecation, and that the larvse migrated to the stomach until about 

 fully developed. Yallisnieri and Eeaumur made the same erroneous 

 diagnosis. 



