Ctenoplematine Ichneumonidae were sampled with Malaise traps, primarily from central Texas, and dissected to explore variation in reproductive tract morphology, egg size, and egg load. A few species representing the subfamilies Xoridinae, Labeninae, Poemeniinae, Ophioninae, Banchinae, and Tryphoninae were examined for comparison. All ctenopelmatines were synovigenic, but egg size and egg load were highly variable among species. Eggs of koinobionts were always smaller than eggs of the idiobiont taxa Labena, Podoschistus, and Xorides, even after adjustment for body size. Egg loads of koinobionts were significantly larger than those of idiobionts. We discuss our findings in the context of the idiobiont/koinobiont dichotomy and associated life-history traits.