Spent poultry litter use as a fertilizer in horticulture supports stable fly Stomoxys calcitrans (L.) (Diptera: Muscidae) development. Stable fly continues to have an economic impact on livestock production and rural lifestyle in south-western Australia. The use of raw poultry manure is banned in 12 Shires surrounding Perth. The loss of market options for West Australian broiler growers has caused economic hardship. Hence, this study examined a range of chemical and biological amendments to spent poultry broiler litter in preventing stable fly and nuisance fly development. These included alkalizers (i.e., lime sand, quicklime, soda ash, and shell grit), acidifiers (aluminum sulfate, sodium bisulfate), gypsum, zeolite, spongolite, calcium cyanamide, and two fungal agents. The treated litters were placed under irrigation in horticulture with amendments added prior to them being exposed in the field as replicate 1-liter pads. In total, 19,559 stable flies developed from the spent litters exposed over five field experiments (88.7% of all flies recovered). House flies (Musca domestica L. (Diptera: Muscidae); 2,067 or 9.4%), false stable flies (Muscina stabulans Fallén (Diptera: Muscidae); 414 or 1.9%), and two sarcophagids (flesh fly) also developed from the litter. Borax completely prevented any fly development from the litter. Calcium cyanamide (1-2.5% v/v) and sodium bisulfate (10%) reduced stable fly numbers by as much as 99-100% when added to litter. Alkalizers, zeolite, spongolite, and entomopathogenic fungi had no significant impact on stable fly development. The addition of either calcium cyanamide or sodium bisulfate to raw litter can boost the fertilizer value of the litter while preventing stable fly development.