THE CANADIAN ENTOMOLOGIST 247 



On October 2 and 3, 1917, while in camp on the East Verde 

 River, Arizona, at a point about eight miles north of Payson, 

 altitude 4,400 feet, I took two femalesof nasalis, and noted others, 

 flying at the throat of my horse, but in no case did they alight 

 there. They were seen to hover directly under the animal's 

 throat, and then dart suddenly at the muzzle. I saw this opera- 

 tion repeated many times before I was able to capture the fly, as 

 this action of darting at the muzzle made the animal especially 

 wild. On examination im.mediately thereafter, I found several 

 whitish eggs with their sharp bases penetrating and adhering in 

 the skin of the upper lip. These eggs were lost owing to the frantic 

 struggles of the horse at the time, but similar eggs were dissected 

 from the abdomen of the fly. 



The egg is practically the same size and shape as that of 

 intestinalis and not at all like that of haemorrhoidalis, but the 

 anal end is moderately pointed though somewhat blunt as seen 

 under a high power. It is capable, however, of penetrating tender 

 skin, as tested on the back of my finger. Moreover, the chitinized 

 clasping forceps at the end of the heavy ovipositor are quite sharp 

 in nasalis, while they are decidedly blunt in both intestinalis and 

 haemorrhoidalis . 



On the East Verde intestinalis was common but caused no 

 such alarm as did nasalis while ovipositing. No specimen of 

 haemorrhoidalis was seen anywhere in that region. 



The above facts seem to indicate that nasalis oviposits about 

 the muzzle of the horse, hovering under the throat merely as a 

 preliminary while seeking a good opportunity to dart at the lips, 

 and piercing the tender skin with the sharpened forceps of the 

 ovipositor while thrusting the anal end of the egg into the puncture. 

 It seems further that this habit of darting at the muzzle of the 

 animal was known to Linnaeus, else why should he have named 

 the species nasalis? It appears that in later times the preliminary 

 action of the fly in seeking the throat has been commonly observed 

 and its darting thence to the muzzle, overlooked by some investi- 

 gators though recorded by others, hence the mistaken opinion still 

 held by some that it oviposited in the region of the throat. It is 

 against all reason that the eggs should be placed under the throat, 



