490 Observations on the Development of Ox Warhle, 
XIX. — Observations on the Development of Ox Warble, and 
Warble Maggot. By Eleanok A. Ormeeod, F.R.Met.Soc, 
Consulting Entomologist to the Royal Agricultural Society. 
The following observations on the Ox Warble-maggot are an 
endeavour to describe the changes, both in external form and 
internal structure, which it passes through so rapidly (from the 
time it is first noticeable in the opening warble until it gains 
the shape in which it is best known), that little notice appears 
as yet to have been taken of the details. The constant supply 
of fresh specimens of hide and of living maggots with which 
I was favoured during the last spring,'enabled me to watch their 
habits and their method of growth almost from day to day, and 
in many respects these bear so practically on the direct method 
of injury to the infested cattle, and on the manner in which 
the opening in the warble is formed and enlarged, that the 
shortest possible description of them may be of some interest. 
Fig. l.—Ox Warhle Fly, 
Hypoderma bovis (Degeer) 
Fig. 2. — Cltannel through hide, 
much magnified. 
The commencement of the attack had been noticed in the 
previous November in the form of small inflamed patches or 
swellings on the flesh-side of the hide, within which the maggot 
lay free — that is, not enclosed in a cell — -and down to which 
swellings a fine channel passed from the upper surface of the 
hide. ^ 
This channel appeared to have no lining membrane, but to 
be merely a passage gnawed or torn by the mouth-hooks of the 
maggot, and (as in Fig. 2) sometimes slanting, or taking a straight 
course, or so completely curved at the upper part of its course, 
that it was impossible that the channel where this curve existed 
could have been formed by the ovipositor of the fly ; conse- 
quently, as the method of egg-laying may be presumed not to 
vary (to all appearance), proving that the egg from which -the 
maggot hatched was laid either outside or just beneath the outer 
cuticle of the hide. 
Careful watch was kept both on living cattle and newly-flayed 
hides in various localities throughout the winter, in order to 
