When the maggot is full-grown it is about an inch long and 
dark grey; it presses itself out of the opening tail foremost, and 
falls to the ground, where it finds some 
shelter, either in the ground or under a 
stone or clod, where it changes to a 
chrysalis. The chrysalis is dark brown 
or black, much like the maggot in 
shape, only flatter on one side ; and 
from this brown husk the Warble Fly 
comes out in three or four weeks, but 
this length of time is increased by cold 
weather. 
With regard to methods of remedy, there does not appear to be 
any difficulty of getting rid of the Warble-maggot easily and 
cheaply, when the Warble has “ripened”—that is, opened so far 
that the black end of the tail is visible. Then it may be destroyed 
cheaply and quickly. From special observations, taken during the 
last three years, it has been found that where the Warble-maggots 
have been destroyed before they drop from the cattle, there is little 
if any summer attack of Warble-flies. Consequently the cattle can 
rest in peace, and, as there is very little egg-laying on them, there 
are scarcely any Warbles in the following spring. 
Squeezing out the maggots is a sure method of getting rid of 
them, but they may be destroyed easily and without risk by 
dressing the Warble with a little of McDougall’s smear or dip, or 
by a little cart-grease and sulphur, applied well on the opening of 
the Warble. Mercurial ointment answers, if carefully used—that 
is, in very small quantity, and only applied once as a small touch on 
the Warble ; but where there is any risk of careless application it 
should not be used. Any thick greasy matter that will choke the 
breathing-pores of the maggot, or poison it by running down into 
the cell in which it lies and feeds, will answer well; and lard or 
rancid butter mixed with a little sulphur has also been found to 
answer. Tar answers if carefully placed, so as to be absolutely on 
the hole into the Warble. Bought cattle are often badly infested, 
and need attention. 
To prevent fly attack in summer, train-oil rubbed along the 
spine, and a little on the loins and ribs, has been found useful; so 
has the following mixture :—4 oz. flowers of sulphur, 1 gill spirits 
of tar, 1 quart train-oil; to be mixed well together, and applied 
once a-week along each side of the spine of the animal. With both 
the above applications it has been observed that the cattle so 
dressed were allowed to graze in peace, without being started off at 
the tearing gallop so ruinous to flesh, milk, and, in the case of 
cows in calf, to produce. 
A mixture of spirit of tar, linseed oil, sulphur, and carbolic 
acid, has also been found useful; and anything of a tarry nature 
is useful, as sheep-salve (or bad butter and tar mixed with 
sulphur), or Stockholm or green tar, rubbed on the top of the cows’ 
backs between the top of the shoulder-blade and loins. Washes of 
Section of Warble, after 
soaking in water. 
