THE STABLE FLY. 
13 
The pupa.—When the larve are full grown they shorten and 
become thicker, and the skin contracts and hardens to form the case 
in which the transformation to the adult is to take place. This 
puparium, or pupal case, is rather soft and yellowish at first but soon 
becomes harder and changes to a reddish brown color. 
It is elongate oval, slightly thicker toward the head 
end, and from one-sixth to one-fourth of an inch in 
length (fig. 3). During this stage the insect is com- 
pletely dormant, the transformation from maggot to 
adult fly going on within the puparium. This rest- 
ing stage requires from six to twenty days, or in cool 
weather considerably longer. 
The adult.—When the fly has completed its de- 
velopment within the puparium it pushes its head 
against the end until the shell splits open. It then 
crawls out as an adult fly but so different from the 
fly ordinarily seen that one would scarcely recognize 
it. The color is pale and the head considerably pro- 
duced in front between the eyes. At this time the 
wings are only small, wrin- 
kled sacs. In a few minutes 
air is forced into the wings, 
and they slowly unfold, the 
fly becomes gradually darker 
in color, and its body becomes 
harder. Up to this time the 
beak is not visible, as it is bent 
downward between the legs. 
Tt soon becomes almost black 
and is brought forward in its 
natural position so that the 
tip may be seen from above. 
2 
C4 
Fic. 3.—The stable fly: Pupa. sixteenthsof an inch in length. 
Greatly enlarged. (Original.) 
Fia. 2.—The stable 
fly: Larva or mag- 
got. Greatly en- 
larged. (Original.) 
When completely dried out the adults show 
four rather distinct, dark, longitudinal mark- 
ings on the thorax, as well as several dark 
spots on the abdomen. The male is usually 
slightly smaller than the female, the body 
of which measures from one-fourth to five- 
The adult,as 
seen from above, is shown in figure 4, and a side 
view of a female specimen engorged with blood is shown in figure 5. 
This insect is closely related to the house fly, as can be readily seen 
by its close resemblance to that insect. It may be distinguished 
from the house fly, however, by the long, sharp, biting mouth parts, 
é 
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