However, this does not appear to be the case, at least in the open-sided poultry houses in California where this idea was tested. Here manure dries rapidly so it isn't suitable for fly oviposition or development for very long, and manure can be left to accumulate for several months. During this time natural enemies, such as hister beetles and a mite, destroy up to 97% of the immature filth flies in the manure. The presence of undisturbed manure near new manure deposits usually made no difference in reestablishment of these predators. Besides, producers rarely do a perfect cleanout anyway, scattering enough small manure chunks to seed natural enemies into areas which will later receive new droppings.

The benefits of alternate manure removal do not seem to justify the more frequent need to carry out what producers regard as a necessary but distasteful task, at least in this system. It may be of more benefit in a closed type of system.

Source:

Mullens, B. A., N. C. Hinkle, and C. E. Szijj. 1996. Impact of alternating manure removal schedules on pest flies (Diptera: Muscidae) and associated predators (Coleoptera: Histeridae, Staphylinidae; Acarina, Macrochelidae) in caged-layer poultry manure in Southern California. J. Econ. Entomol. 89: 1406-1417.