Body size, an important life history correlate of fitness, is often influenced by conditions experienced during development. Variation in clutch size in particular can influence body size when clutch members compete for limiting resources. In parasitic wasps, larger clutch sizes can lessen the negative affects of interspecific competition when larvae outnumber or kill larvae of competing species. Conversely, larger clutch sizes can increase intraspecific competition for limited host resources. Large clutch sizes in parasitic wasps are thus often associated with decreased individual body sizes. We explore the possibility that this relationship may or may not be a life history invariant, or a relationship shared across multiple species, in parasitic wasps. Tibiae and clutch sizes are measured in parasitic wasp species with highly variable clutch sizes, and the clutch size-body size relationship is compared in single-sex and mixed-sex broods. Also, broods of non-sibling conspecific larvae are compared to broods of only siblings.