Nephila spiders are famous for extreme sexual size dimorphism, with females an order of magnitude larger than males. The proximal developmental mechanism for the sexual size dimorphism is extended development in females: they have many more juvenile instars than males. During an experimental rearing of Nephila clavipes (Linnaeus 1767) from two populations, we discovered that females cannot reach sexual maturity on diets that are qualitatively and quantitatively sufficient for male maturation. Here we describe the dietary regimes that produced sexually mature females and the life history implications of these requirements.