Most spiders do not live but a few months because predators, parasites, and diseases kill them long before they age to death. Those that complete their life cycle typically last at least a year, however, from egg stage to adult. Spiders kept in captivity have demonstrated surprising longevity, however. Some female tarantulas, for example, may live over twenty years. Depending on the species, they may not even reach adulthood for several years. Spiders in the genus Sicarius, from deserts in South America and Africa, can live to nearly 15 years. Web-spinning spiders probably do not survive longer than one to three years, even under optimal conditions.