Sparassid huntsman spiders are caring mothers, aggressively guarding egg sacs and newly emerged young. Only a single endemic Australian huntsman species, Delena cancerides, has significantly prolonged the period of maternal and sibling association to produce multigenerational matrilineal colonies under the bark of trees. In Australia, solitary huntsman species live under bark in the same habitats as Delena. Body size, use of retreats, and aspects of natural history are comparable among these huntsman species. The contrast between huntsman social traits and similarity in other variables provided an opportunity to comparatively assess costs of group-living. In laboratory studies, I compared development, early interactions, patterns of prey sharing, cannibalism, and growth in 11 solitary huntsman species with social Delena to comparatively assess costs of group-living. Developmental patterns differ significantly between Delena and the other species. Delena develop much slowly, do not disperse, share prey regularly, survive and grow better in groups. In contrast, the solitary species explosively disperse by the 4th or 5th instar, only share prey with their siblings during the youngest instars, never acquire prey from their mother, and cannibalize each other. There are many social benefits of group-living for young Delena, but comparable benefits are not seen in the solitary huntsman species.