The previously unknown biologies of three species of bud mining sawflies occurring in the central Sierra Nevada Mountains are compared. All three species oviposit in the buds of white fir, Abies concolor, but in different parts of the bud. Each has a different ovipositional posture as well. The first instar of each species mines the bud in a characteristic manner; later instar larval behavior is not distinguishable. The larvae cannot be separated morphologically, but the adults are easily recognized by their genitalia. At moderate population levels competition does not appear to be a major limiting factor even though the three species occupy the same niche. The feeding of Pleroneura aldrichi, P. koebelei, and P. lutea appears to have little if any effect on the host tree.