The most ideal manure management program is to clean frequently and spread the manure thinly on fields where it will dry quickly. The pest flies larvae are highly susceptible to this drying and will not pupate (form their cocoon) properly unless the medium they’re in is moist. If frequent cleaning is not practical and the manure accumulates to more than 2 or 3 inches deep, it should be stacked in a large pile. This will reduce the surface area and the heat generated in the core of the pile will force the pest fly larvae to the outside 6 or so inches.
Fly Predators live their entire life on or near manure and are partially transported wherever it goes. Cleaning will disturb the adult Fly Predators and they will fly off and migrate to new manure deposits. You may lose someof the next generation of Fly Predators that have not yet emerged from the fly pupa, but they will travel along to wherever the manure is taken and give control to that area. Often it is best not to clean down to the ground, but leave an inch or two of manure, this will also help your natural population of beetles and mites which also help control pest flies.
One important fly-breeding site that is often overlooked is moist decaying vegetable matter. Rotting hay and straw spilled behind feeders and even lawn clippings offer an excellent breeding site for pest flies. This vegetable matter should either be removed or spread out so that it will dry.
Another fly-breeding site that is often a problem is where livestock urinate on their manure, keeping it moist. If removal is not practical then sprinkle with hydrated lime (available from farm supply houses). This prevents flies from breeding and helps the odor. In fact, it is a good practice to put lime on all sites where your livestock urinate, but do not put it on manure where Fly Predators will be.
If I spreading the manure, doesn't that defeat the use of the predators?
I only have grass in my backyard where the flies are bad, other than the chicken coop. How and where do I spread the fly predators?
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