The boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), is a major pest of cotton (Gossypium spp.) that overwinters in an adult diapause. Diapause is primarily induced by adult diet, but late-season cotton, postharvest regrowth, and volunteer cotton also support reproduction, especially in the subtropics and tropics where conditions permit cotton fruiting during the fallow season. When cotton plants escape crop destruction efforts they may produce fruit and become heavily infested by overwintered weevils. The ecological implications of these plants to survival of overwintered weevils have not been studied. We examined the physiological and survival responses of trap-captured overwintered weevils to starvation and to square (reproduction-promoting) and boll (diapause-inducing) diets. Few newly captured overwintered weevils exhibited fat body hypertrophy or gonadal characters of diapause. Square feeding rapidly induced a high level of reproductive development in both weevil sexes but little fat accumulation. Compared with the square diet, a boll diet promoted more gradual reproductive development in female weevils, but also stimulated in both weevil sexes the development of hypertrophied fat bodies similar to those associated with diapause. Although diapause was not reinduced by the boll diet, resulting accumulations of fat allowed substantially greater host-free longevity compared with overwintered weevils that were not fed. The contributions of diapause and fallow-season reproduction to boll weevil overwintering survival are commonly recognized. Findings of this study identify an additional mechanism by which overwintered boll weevils may utilize fallow-season cotton to enhance survival, and reinforce the importance of eliminating cotton during the fallow season.