DESCRIPTION OF THE MAGGOT. 
changes, as above mentioned, to a more pear-shaped form, placed 
with the smallest end (containing the minute horny spiracles at its tip) 
uppermost, and thus with the compact liard-tipped apparatus above, 
and the growing body behind, is well calculated to force open and 
enlarge the passage down which it came. 
The size and shape of the perforation through the hide altered 
progressively with the growth of the maggot. At first this passage 
was very little larger at the lower than at the upper opening; and, 
though the walls of the perforation had now become smooth and 
shiny, I could not distinguish the presence of any distinct lining 
membrane. With the enlargement of the passage its shape became 
more cone-like (corresponding with the altering form of its tenant); 
and, on March 5th, I found for the first time a distinct pellicle or skin¬ 
like membrane covering the walls of the perforation, or passage, and 
continuous with the lining of the maggot-cell below. 
The great change, both in the appearance and the internal structure 
of the maggot, took place when it was grown to about a third of its 
full size, when it assumed its well-known 
shape. Previously to this, whilst the work 
of forming its passage was still in progress, 
its chief characteristics externally were the 
absence of everything that could obstruct 
its power of pressing onwards; and inter¬ 
nally it was little more than a bag of fluid, 
with a large proportion of the space occupied 
by breathing-tubes ,—a very important con¬ 
sideration relatively to available methods 
of destroying the creature. At the period, 
however, of its moult to its final stage a 
change takes place respectively in the nature, 
or in the amount, of development of nearly 
the whole of both the internal and external structure of the maggot* 
The hard tips necessary, or at least serviceable, for forcing a passage 
up the hide, are no longer needed, and they are exchanged for a broad 
form of spiracle (fig. 8, p. 8), and the internal organs become suited 
to provide material for the development of the fly, which will pre¬ 
sently form in the dry husk of the maggot which serves as the 
chrysalis-case. 
In methods of destruction of warble-maggot a large proportion turn on 
choking up their breathing-apparatus . This consists mainly of two 
large breathing-tubes, or trachea, which draw in air at the tip ot the 
tail by two perforated bodies known as spiracles (see fig. 5). 
From the earliest stages which I had opportunity of observing up 
to date of change mentioned in preceding paragraph the general form 
Fig. 5.—Breathing-tubes of 
maggot, magnified. 
