THE STABLE FLY. 15 
DEVELOPMENT AND HABITS. 
BREEDING PLACES. 
Horse manure has long been considered the normal breeding 
medium for this pest. Investigations made during the outbreak in 
1912 showed clearly, however, that the vast majority of the flies bred 
out in straw stacks, and investigations made around stables and 
barns indicate that while the fly breeds in pure horse manure it 
favors a mixture of this substance with straw. The fly was found 
to be breeding in much greater abundance in oat straw than in wheat 
straw. This appeared to be due to the softer stems and the greater 
amount of leaves in the oat straw, which furnished better food and 
allowed the stacks to become more compact. Rice straw was also 
found to furnish suitable breeding conditions, and there is little doubt 
that barley and rye also often serve as food for the immature stages. 
, 
Fic. 5.—The stable fly: Adult female, side view, engorged with blood. Greatly enlarged. (Original.) 
As has been stated, it was found by Prof. Iches to breed in great 
numbers in the débris left after thrashing flax. A careful exami- 
nation of portions of alfalfa stacks which were moist and readily 
accessible to numbers of flies showed that they were not infested. 
This was also found to be true of accumulations of weeds and 
bunches of grass in open fields. It is probable, however, that the 
insect may occasionally breed in broken-up masses of hay or dead 
grass, especially when they are permeated with liquids from manure. 
The manure piles commonly found by stables where horses are kept 
furnish suitable breeding conditions. This is especially true in the 
early spring, when the warmth of the manure appears to be very 
attractive to the flies for egg layimg. Cow-lot manure which has be- 
come broken up, especially when mixed with waste feed, is also utilized 
as a breeding place for the insect. This has also been found to be true 
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