ScerGAL4GMR19C03 drives strong expression in the circular midgut muscle of the copper cell region of the adult middle midgut (adult midgut regions R3a and R3b), and highly variable expression in the circular midgut muscle of the anterior and posterior midgut. Expression levels in the adult midgut circular muscle are stronger than that of ScerGAL4GMR19E03. ScerGAL4GMR19C03 also drives expression in terminal filaments and in germarium cap cells in the germarium.