Mites associated with bark beetles feed and reproduce in subcortical habitats engineered by their vectors. These mites lack the ability to disperse independently, but have evolved behaviors that facilitate using beetles for transport between patchy resources. This research addresses interactions between communities of phoretic mites and their bark beetle hosts, with emphasis on Ips spp. in Wisconsin. I first determined the major mite species, and quantified their frequencies of association, with beetle hosts. Nearly 78% of I. pini in Wisconsin red pine stands carried phoretic mites, and the three predominant species included one each from separate feeding guilds. Mites varied in diversity across geographic regions, and members were more abundant on beetles captured later in their flight season. I expanded this analysis to incorporate a landscape scale and additional vector species. Approximately 21 mite species were associated with 36 beetle species in Pinus stands in southern Wisconsin, northern Arizona, and northern Georgia. While host beetles carries largely similar mite species across regions, there was high variation in species composition among host beetle species within each region. I evaluated potential impacts of mites on beetle fitness, using a two-part approach. On field collected Ips grandicollis collected in baited traps, there was a positive relationship between beetle emergence and several mite species. In laboratory experiments where the abundance of mites on beetles was manipulated, however, there was no relationship between colonization rates or total emergence of beetles and mite prevalence. This suggests a correlative rather than causal link between beetle reproductive success and mite prevalence. I conducted a series of experiments to characterize the behaviors of mites commonly associated with Ips, with an emphasis on the poorly understood, non-dispersal life stages. Mites were found to be highly specific in the body parts on which they attach to beetles. Further, they detached from beetles in response to cues associated with both beetle and tree hosts, and discern among living, dead, and injured beetles. Within plant tissue, movement by mites can be elicited by phloem volatiles. Fungal symbionts of beetles, but not opportunistic fungal invaders, provide a food resource that benefits mite fitness.