We reared newly hatched Phaon Crescent butterfly larvae to the adult stage on a completely artificial diet. About 37% of first instars survived to the adult stage. Addition to the diet of freeze-dried host plant leaves equal to 10% by weight of dry ingredients produced up to 66% survival to the adult stage. Survival of larvae and production of adults on the artificial diet without host plant leaves was increased to equal that of diet with host plant leaves by adding 5% glucose or 5% Beck's salt mix. Although the ovaries of females produced on host-free artificial diet appeared to be mature at emergence and contained mature-looking eggs, we never obtained viable eggs from them. In contrast, females produced on the artificial diet containing at least 10% by weight of freeze-dried host plant leaves laid viable eggs, and four successive generations were reared on the artificial diet with 10% freeze-dried host plant leaves. Males produced on the artificial diet without host plant tissue displayed abnormalities in the shape of the testes and parts of the vas deferentia, compared to males reared on the diet with freeze-dried host leaves or on living host plants. The role of host plant tissue in nutrition and reproduction of both male and female Phaon crescents remains to be determined.