Manure is removed with flushing and/or scraping systems. If the systems are properly designed and function properly, most fly breeding will be eliminated by frequent cleaning, carried out every day or two.
However, it is common for these systems to leave pockets of manure which support fly breeding. Corners, edges and areas under railings and fences are missed by the equipment. Broken scraper cables or low water pressure cause these automatic systems to fail, or do an incomplete job of manure removal. Crusting and caking of manure causes accumulations that cleaning equipment cannot remove.
Daily or very frequent manure removal leads to the problem of manure disposal. If the manure is spread immediately on fields in a very uniform thin layer, there will be no fly breeding. However, if the manure spreaders leave large clumps, then breeding may occur. Adding water to produce a slurry of manure facilitates spreading although this may increase odour problems.
Other options for disposal are to pile the manure or flush it into a deep lagoon for anaerobic decomposition.
Piles of manure will breed flies unless compacted and covered (for example with plastic sheeting), causing the temperature in the pile to become too high for fly survival.
A properly designed and managed lagoon will not breed flies. However, if the lagoon is overloaded with too much manure for its size, there may be floating mats of manure and debris which will support fly breeding.
An alternative to disposal by flushing into an outside lagoon is flushing into a pit containing water beneath the floor of the animal housing. This method is commonly used in slotted-floor swine houses. Periodically the pit has to be flushed or pumped out into an outside lagoon or spread on the fields.
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