THE BEEEZE FLY. I4t 
In the months of May and June, these swellings may 
be found in great plenty. They are mostly seen upon 
young cattle, and as a general rule. are situated close to 
the spine. So common indeed are they, that out of a 
whole farm-stock of cattle I have seen almost every cow 
under the age of four years attacked by the Breeze Fly, 
and counted from two or three to twelve or fourteen 
upon a single animal. It is said that as many as forty 
have been detected upon a single cow, but such an event 
has not come within my own observation. 
The swellings caused by the Breeze Fly are called 
Wurbles, or Wornils, and can be easily detected by 
passing the hand along the back. Strangely enough, the 
cow does not appear to feel any pain from the presence 
of these large parasites, nor dves she suffer in condition 
from them, although it would seem that they must keep 
up a continual drain upon the system. Indeed, some 
experienced persons have thought that, instead of being 
injurious, they are absolutely beneficial. 
When the grub has reached its full development, it 
' pushes itself backwards ont of the gall, and falls to the 
ground, into which it burrows. Presently, the skin of 
the pupa becomes separated from that of the larva, and 
the latter dies, and becomes the habitation in which the 
pupa lives. The head portion of the skin is so formed 
that it flattens when dry, and can easily be pushed off, 
like the lid of a box, permitting the perfect fly to escape. 
Even when the insect is still in its pupal condition this 
lid can be removed, so that the pupa can be seen within 
its curious habitation. I may mention here that insects 
which are thus covered while in their pupal state, so as 
to show no traces of the creature within, are said to 
undergo a “coarctate” metamorphosis. Nearly all the 
_diptera are examples of the coarctate insects. 
