It is well established in Traditional Chinese Medicine that certain natural products, such as male silkworm moths, have different therapeutic effects on men than on women. These natural products have been used as dietary supplements specifically formulated for men or for women. However, this presumed sex-specific effect of certain natural products has not yet been confirmed experimentally with animal models or in human clinical trials. Here, using the fruit fly (Drosophila melanogaster) as a longevity model, we examined the effect of hu-bao (HB) and seng-bao (SB), two marketed health products made from a mixture of natural ingredients. Our results convincingly demonstrate that the effect of HB and SB are indeed specific for the male fly. The life-span of the male was significantly increased when HB or SB was added to the culture medium. In contrast, neither HB nor SB had much effect on the female fly. Upon removal of the male silkworm moth ingredient from HB or SB, the life-span prolongation effect of HB and SB was drastically diminished. Only with the addition of the male silkworm moth did the culture medium show a statistically significant life-span prolongation effect. This result suggests that the male silkworm moth is a key ingredient, in combination with other components, for specific prolongation of the life-span of male flies.