Two spider-boarding mantispids, Mantispa uhleri Banks 1943 and Climaciella brunnea (Say 1824), were found to be partitioning available spider egg resources in an Illinois woods based on vertical stratification. Mantispa uhleri was found to be phoretic on the philodromid Philodromus vulgaris (Hentz 1847), the salticid Metacyrba undata (De Geer 1867) and the anyphaenid Aysha gracilis (Hentz 1847) at levels of 75%, 26%, and 27% respectively. All of these spiders were collected from areas above the forest floor. In contrast, C. brunnea was collected from 19% of leaf litter-inhabiting lycosids of the genus Schizocosa. There was no host range overlap within the woods, but in a grassy field without appreciable stratification of vegetation adjacent to the woods, both M. uhleri and C. brunnea were found aboard the lycosid Rabidosa punctulata (Walckenaer 1837) at levels of 2% and 7% respectively. A single larva of Mantispa pulchella (Banks 1912) associated with an anyphaenid from the woodland sample was also collected in this study. Mantispids are far more common than has been previously supposed and are likely an important factor in spider population dynamics and the evolution of spider behavior.