14 BTLLETIX 597. U. 5. DEPAETMEXT OF AGRICULTURE. 



proceeds from infuriated shaking of the head, sometimes accompanied 

 by loud snorts, to complete loss of self-control, and Trill use any 

 means for self -protection. Numerous runaways naturally occur and 

 serious accidents have also occurred when horses were being used 

 for mowing. The majority of farmers and breeders contend that 

 " the fly stings the horse in the nose." The reactions of the animals 

 are often so violent that at first it seemed that the horses really 

 experienced pain. Dr. Parker, of the Montana State Board of 

 Entomology, has published some notes 1 to the effect that the eggs 

 were thrust into the skin, but he failed to recognize the minute hairs 

 to which the eggs are attached. The pointed portion of the egg is 

 merely a device by which it is attached to the hair. A horse does 

 not experience any pain, as the ovipositions do not puncture the skin. 

 Neither do the flies deposit in the nostrils. Careful search has 

 failed to disclose a single egg in such locations, and it would appear 

 that the snorting of the animal has given rise to this " popular 

 opinion." It is believed, however, that annoyance is largely due at 

 first to an instinctive fear and later to a tickling sensation when the 

 eggs are attached to the minute hairs, as the lips are the most sensi- 

 tive portions of the horse. Practically all horses in this section have 

 sore lips from eating a " wild barley " or " foxtail grass " (Horrfeum 

 pjbatum ) and there is no doubt that this soreness contributes to 

 the annoyance. 



NATURAL PROTECTION OF HORSES. 



The flies show no preference as to type, breed, color, or age, but 

 naturally oviposit upon unprotected animals. Horses seek protection 

 in pastures, the individuals gathering in a bunch and resting their 

 lips upon one another. Colts and young animals not high enough 

 to protect their lips in this way receive an abundance of eggs. 



A horse will sometimes hold the lips upon the ground as if grazing, 

 upon detecting the presence of the fly. and when held in such posi- 

 tion the adult fly is rarely observed to oviposit. Often the annoyance 

 of biting flies and other depositing Gastrophilus will cause a horse 

 to walk, holding the lips near the ground. Frequently other horses 

 will follow and protect themselves by placing their lips upon his 

 back or the backs of other animals in the line. Usually they search 

 for the highest elevation where the breeze is blowing, or for standing 

 water, but if an open stall is convenient they will use it to good 

 advantage. If protection is not found an uneonfined animal will 

 often wander a great distance from home. 



Upon a bright still day ovipositions occur from S a. m. until about 

 sunset, and the group of horses may be observed to shift from place 



1 See " Bibliography." page 50. 



