The moth Utetheisa ornatrix (family Arctiidae) depends on pyrrolizidine alkaloids (PAs) for defense. It sequesters the toxins as a larva from its food plants (Crotalaria species: family Fabaceae) and retains them through metamorphosis. We report here that PA-possession in the adult female U. ornatrix has a life-shortening effect, suggesting that, by putting the compounds to use, the moth may be incurring a cost. However, PA-possession also induces the female to oviposit at an accelerated rate, so that she does not, by dying earlier, incur a loss in fecundity. We argue that by "compressing" their adult existence into a shorter period, female U. ornatrix may actually accrue benefits.