Larvae of this tiny wasp hollow out the stems (petiole) of sugar maple leaves (Fig. 43). The light yellow larva begins feeding at the base of the petiole and gradually mines its way toward the leaf base. Shortly before it finishesfeeding, it chews through the petiole a mew millimeters from the leaf blade. The blade droops (Fig. 44), eventually breaks away, and falls to the ground.