THE STABLE FLY. 19 
THE LARVA AND ITS HABITS. 
The larve begin feeding as soon as they hatch from the eggs and 
continue to do so throughout their growth. Portions of moist straw 
or other material in which they are breeding are torn off by their 
mandibles, which are located on the narrow or head end of the mag- 
got. When very small they frequently penetrate between the layers 
of the stalk or leaves of grain when moistened in the straw stack. 
When larger they frequently feed within the straws, and transforma- 
tion to the resting state sometimes takes place in this protected situa- 
tion. 
The duration of the larval stage has been found to vary from 11 to 
30 days. During very cold weather this stage is probably consid- 
erably longer than one month. The character and abundance of 
food as well as the amount of moisture present have an important 
influence on the development of the maggots. The larve follow the 
moisture inward as the material in which they are breeding becomes 
dry on the surface. Pupation occurs anywhere in the breeding mate- 
rial; however, it frequently happens that the larve, when breeding 
in small masses of straw or manure, work downward as the material 
dries and pupate at the surface of the soil. 
LIFE CYCLE. 
It has been found that the complete development from the depo- 
sition of the egg to the emergence of the adult fly may be completed 
in 19 days. On the average the period is somewhat longer than this, 
generally ranging from 21 to 25 days where conditions are very favor- 
able. The longest period observed for complete development was 43 
days, although it is certain that in the late fall and during the winter 
months a much longer period is often necessary. The finding of full- 
grown larve and pupe in straw during the latter part of March, 1913, 
in northern Texas shows that development may require about three 
months, as these stages almost certainly developed from eggs depos- 
ited the previous December. 
SEASONAL HISTORY. 
The stable fly is particularly abundant and injurious in the late 
summer and fall. This is especially true in the Northern States, 
where development begins later in the spring. Mr. C. T. Brues states 
that the flies first appear in noticeable numbers about June 1, in the 
vicinity of Boston, Mass. The fly has been observed to be sufficiently 
numerous to annoy cattle considerably at Dallas, Tex., as early as 
March 1, and in the western part of Texas it has been observed feeding 
on live stock in considerable numbers early in May. At Batesburg, 
S.C., Mr. E. A. McGregor found the adults to be commonly attacking 
live stock about the middle of March in 1913. In the extreme south- 
ern part of the United States, however, there is no month during the 
year in which flies are not annoying to horses and cattle. 
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