The efficiency of Bacillus thuringiensis (B.t) as a microbial housefly control agent was evaluated in one of the natural maggot breeding medium, namely poultry faeces. Two commercial formulations, a wettable powder and a liquid concentrate were assayed against Musca domestica sorbens in synthetic fly breeding madia and in chicken faeces. The latter was found to favour maggot breeding when compared with the synthetic one. Both formulations resulted in significant reduction in maggot numbers,, pupal development and adult emergence. Concentration was found significantly affecting adult emergence. The liquid concentrate induced higher larvicidal activity than dry powder formulation. Contaminated faeces produced from orally fed chickens were found significantly toxic to the breeding maggots, reaching maximum larvicidal activity till the 4th day post-feeding faeces, and continued in less activity till the 6th day. Adding B.t. in chicken food in poultry mass breeding is recommended for housefly control.