The boxelder leaf gall midge is univoltine in Michigan. Adults emerge after the first few warm days in April, and deposit numerous eggs within the folded young leaves of boxelder (Acer negundo L.). Larval eclosion occurs a few days later, and gall development begins shortly after. Head capsule measurements revealed three larval instars. Third-instar larvae drop to the ground near the end of May, work their way into the soil, and construct cocoons. Pupation occurs in late August, and overwintering takes place in the pupal stage. Because oviposition occurs almost always on leaves in a certain stage of development and an estimated 50% of leaves will therefore escape attack, host mortality apparently cannot be caused by this insect.