Dilutions of honey, sucrose solutions, pollen extract, and combinations were given ad lib toStomoxys calcitrans(Linnaeus) adults. Pollen diffusates in water increased stable fly longevity more than all other diets. Flies given pollen diffusates in sucrose solutions or honey dilutions had significantly lower longevity than those given pure pollen diffusates, indicating that dietary sugar content, rather than protein, dictated release of these materials to the midgut. Whole pollen did not increase stable fly longevity over that of controls. Adult stable flies were kept alive on pollen diffusates for up to 20 days after emergence.