24 
which has contracted so as to form a case for the developing 
fly within. The chrysalis state generally lasts from 20 to 30 
days ; but this period may be lengthened by cold weather, 
especially severe night chills. 
Where the plan has been adopted of killing the maggots 
in the warble in April and May by various applications, there 
is found to be absence, or very slight presence, of Warble Fly 
attack ; and where the maggots have not being destroyed, the 
cattle have been found to be attacked as a regular thing. If 
as soon as the warble is perceptible to the touch, and the 
opening has formed, it is dressed with a little mercurial 
ointment, the maggot will be killed at the beginning of the 
sore, instead of after it has been established several months. 
The maggot may be pricked, stabbed, or poisoned in a variety 
of ways, or it may be killed after coming to maturity by 
being pressed out. Tar applied to the warble has been found 
to kill the maggot; and many other applications which would 
poison or choke it would do equally well. Although this 
treatment in April and May is so far good that it lessens 
coming attack, it is after the cattle have been undergoing the 
drag on their system by the dozens or scores of maggots, that 
the damage to the hide has been done. What is really 
wanted is that egg-laying be prevented, or that the maggot 
be destroyed in the warble when it first bursts. In the 
United States it has been found that a little mercurial oint¬ 
ment, rubbed on the swellings in autumn, acts very well in 
killing the young maggot; but the simpler and equally 
effectual way is to rub the sides, and especially the backs, of 
the cattle with kerosine oil. Prof. Riley, State Entomologist, 
U.S.A., said it was the custom to give one rubbing along the 
back and loins with kerosine oil, or with mercurial ointment, 
in autumn, when the grub was accessible in the hide, and this 
was enough to destroy it. Two applications were sometimes 
made. Miss Ormerod thought that the application known as 
kerosine emulsion, in which it is beat and worked with water 
and a small quantity of soap into a kind of cream or lather, 
would be much more effective than the mere oil. 
Piercing the maggot is not perfectly certain to kill it, as 
the operation is not always thoroughly performed. Stabbing 
also appears painful to the cattle, and it is difficult to get at 
