Maternal investment is strongly influenced by the availability of resources. A mother is expected to trade-off allocation to size, number, and sex of offspring to maximize her lifetime reproductive success. Optimal allocation is likely affected by ecological conditions that can alter the costs and benefits of different allocation decisions. When resources are rare, mothers have fewer resources to invest in offspring, likely altering optimal resource allocation. We examined maternal resource allocation to progeny under three different resource levels in semifield conditions for the solitary bee Megachile rotundata (Fabricius). We found that females with access to low resource levels invested less per individual daughter, but the same per individual son, and produced fewer total offspring compared with females with access to greater resource levels. Resource limitation had no impact on sex ratio.