830 
Warhle Flies 
was made and two eggs were found side bv side on a single hair. Another 
fly was seen resting under a cow’s heel. The flies did not seem as active 
or as wild as H. bovis. There were nine head of cattle in the paddock 
and it was observed that only one, the young steer previously mentioned, 
was really terrified. The other calves ran occasionally but did not 
stampede. The cows paid little or no attention and sometimes hardly 
lifted their tails when the fly was ovipositing. 
The last capture of H. Uneatum was made on May 30th. The fly 
was resting on the heel of a cow which was feeding at the time. Indeed 
in the whole course of these observations the fly was never observed to 
strike above the hock. For the first time since warble flies were studied 
here, we have observed oviposition in H. Uneatum, and can confirm the 
statement made by Glaser, that the fly fastens itself more firmly to the 
hairs than does H. bovis, and remains there for a longer time. This is 
of course necessary since it lays several eggs in sequence on the same 
hair and doubtless for the same reason it frightens the cattle less than 
does H. bovis. In my first publication I gave good reasons for the 
statement that H. bovis deposits its eggs singly, and cast some doubt 
upon Riley’s statements about the method of oviposition in H. Uneatum, 
since it showed such a great difference from what I had observed in H. 
bovis. This doubt was perhaps quite legitimate, as Riley had not 
himself seen the fly ovipositing, but had based his statement on the 
observations of an anonymous person. In any case we were both correct 
in what we said regarding the species we were describing. When I 
casually took up this work in 1912, I made the surprising discovery 
that Riley’s finding of the eggs of H. Uneatum, (1892) was the first and 
only record of its kind ; also that the eggs of H. bovis, figured in the 
text-books, had been obtained from flies bred in captivity ; moreover, 
that oviposition in H. bovis had never been described, for the simple 
reason that no one had succeeded in finding the eggs attached to the 
hairs of cattle. 
Another point which Glaser mentions, about H. Uneatum appearing 
before H. bovis, has been confirmed by this season’s work. Glaser 
places the period of hatching, from egg to larva, at about four days. 
At the laboratory here, two out of three eggs hatched in six days. 
These were kept in a vial with moisture, in my pocket. An experiment 
was tried to see if the larvae would penetrate the unbroken skin. They 
were placed upon a portion of shaved skin, on a calf, and kept supplied 
with moisture. One of them remained quiescent the whole time ; the 
other made an apparent attempt to bore through the skin, but after 
