Chewing lice, Geomydoecus and Thomomydoecus, coexist on pocket gophers, Thomomys spp. We investigated the spatial distribution of the 2 genera on their hosts and explored possible mechanisms of resource partitioning by chewing lice. Chewing lice appear to partition available host resources spatially, with Geomydoecus occurring primarily on the lateral and dorsal regions of the host, and Thomomydoecus occurring primarily on the lateral and ventral regions. Although spatial partitioning of the host habitat is evident, it does not appear to be explained by hair diameter. Spatial partitioning of the host's body could be the result of some other factor, possibly temperature or humidity gradients of the host's body.