Flies mostly breed in a few, relatively small areas of the feedlot where there is moist manure, spilt feed, silage, and mixtures of vegetation and feedlot run-off. Fly control should target feedlot sanitation and moisture control in these areas, particularly after major rainfall events as soon as the manure becomes workable.
Feedlot design can be optimised to facilitate fly control. Most design features will be to ensure good site drainage and make cleaning and the removal of potential breeding sites easier or more effective. A useful guide to feedlot design can be found in the National Guidelines for Beef Cattle Feedlots in Australia (pdf).
Manure accumulated under fence lines in cattle pens is one of the major fly breeding areas in the feedlot. Removing this uncompacted manure from under fence lines and outside of pens will reduce fly breeding.
Cattle pens do not need to be completely cleaned out as often if adequate stocking densities are maintained to compact the manure and trample fly larvae.
Manure stockpiles must be managed to minimise their suitability for fly breeding.
Feed spills are commonly found near feed bunks, in the feed processing area, in the hospital pens and horse stables. Remove feed spills promptly and add them to composting manure.
Moist silage provides a suitable substrate for fly breeding. Avoid spills, particularly along the sides of silage pits, and cover the silage pits so that the edges are sealed to reduce fly breeding in this area.
Compost, rather than bury, cattle carcasses. Cover carcasses completely with manure or some other carbon source to prevent blowflies accessing them to breed.
Check regularly for water leaks from taps, pipes or troughs, as they increase the moisture content of manure pads and facilitate fly breeding.
Control weeds and keep grass and other vegetation short, particularly around pens, drains, sedimentation systems and holding ponds.