This study compares the life histories of five hymenopteran species (genus Leptopilina), and aims to identify reasons why developmental time and life span are not correlated in parasitic Hymenoptera, a relationship that is present in many other taxa. Developmental time, life span, body size, and related traits were measured in female parasitoids that eclosed either from hosts of a standard species or from the host species that are naturally used. Phylogenetic controlled tests revealed that body size was positively correlated with fat reserves, starvation time, and egg load. Developmental time was neither correlated with life span nor correlated to host developmental time. We suggest two mechanisms that affect a potential relationship between developmental time and life span in Leptopilina: (i) delayed emergence in species that live in a stochastic environment (fungi), and (ii) host species related plasticity for growth rates. Additionally, variable adult feeding conditions have large effects on life span measures.