The use of hay can contribute to fly production.
There has been an increased use of large round bales of hay which can be moved by tractor-mounted equipment.
The margins of these bales, stored outdoors, provide a suitable habitat for fly breeding after rain, or after the bales have sat on moist ground for a long period of time.
The pad of hay which is often left on the ground after moving the bales provides an excellent habitat for fly breeding.
To prevent fly breeding, hay bales should be covered and stored on pallets to raise them above the ground.
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