Juvenile hormone titer and wing-morph differentiation in the vetch aphid Megoura crassicauda

► JH titer was measured during the development of wing morphs in the vetch aphid. ► Wingless nymphs at the third instar had higher JH titers than winged nymphs. ► JH application inhibited normal wing development in winged nymphs. ► JH may play an important role in wing-morph differentiation in aphid polyphenism.