The xanthene dye, erythrosin B, was evaluated as a surface spray for control of the house fly,Musca domestica, in breeding areas under caged layer chickens. A weekly spraying of an aqueous solution of erythrosin B directly on chicken manure reduced house fly populations up to 94% in small-scale tests and 89% in a large-scale test. Larvae of the associated beneficial species, the soldier fly,Hermetia illucens, were not reduced by erythrosin B treatment. Approximately 80% of the erythrosin B was not recoverable from the manure after one wk.