Refuse from sugar and alcohol industries is rich in organic matter, offering an ideal breeding ground for house-flies. This pest breeds in countless numbers in such substrate, causing severe outbreaks in several counties of the State of São Paulo, Brazil. To control the nuisance, the formula: borax (Na2B4O7) and slaked lime (Ca(OH)2) solutions of 3.18% and 0.35%, respectively, were applied at the channels carrying the waste waters from the alcohol refinery at intervals of 10-15 days. With this method, a very satisfactory control of house-fly populations was obtained at Macatuba, São Paulo, Brazil, between July 1981 and April 1982.