The biology of the genus Paramyiolia was unknown prior to our studies. During a 5-year period from 2003 to 2008, we discovered a population of P. nigricornis in the Great Smoky Mountains National Park and studied its phenology, behavior, host plant, and immature stages at a single site. The flies are univoltine with a flight time of about 6 weeks in the spring. Its larval host plant is a rare, high elevation, southern Appalachian endemic species of Ilex. Males form leks on other plants in the vicinity, where mating was also observed. Females oviposit into leaf petioles of new foliage. First instars burrow to the base of the petiole and into the current year’s new growth of green stem. Mined stems probably drop to the ground where overwintering of larval or pupal stage is presumed to occur.