Abstract: Recent results of laboratory bioassays and comparative field treatments withBrevibacillus laterosporus (Bl) and azadirachtin [AZ] are discussed in order to evaluate their use incombination or integration, to suppress house fly immatures in natural breeding sites of animalfarms. As determined by laboratory bioassays, the lethal effects of Bl and [AZ] are concentrationdependent and the estimated median lethal concentrations (LC50s) for second instar larvae are1.7×108 spore/g and 24.5μg/g of diet, respectively. Applications on the manure-covered cow pen indairy farms, at a dosage of 3l/m2, and concentrations corresponding to LC50 levels caused asignificant fly development depression in areas treated with [AZ] (63%) and Bl (46%), compared tothe control. Preliminary laboratory observations show compatibility and interactive effects of Bland [AZ]. Therefore, the integration of these generally regarded as safe natural insecticides ispromising.