Recent global warming has caused the maize orange leafhopper, Cicadulina bipunctata (Melichar), to proliferate in Kyushu, Japan. This leafhopper feeds on several species of poaceous plants. Some host plants such as maize, rice, wheat and oats show abnormal growth, characterized by stunted growth and swelling (upheaving) of leaf veins when attacked by C. bipunctata. This abnormal growth is not caused by a virus or phytoplasma, but by the injection of chemical(s) from the leafhopper into the plants. In central and southern areas of Kyushu, serious damage arising from this abnormal growth is known as maize wallaby ear symptom (MWES) and occurs on forage maize during the second cropping season (from late June to November). The degree of MWES is highly dependent on the level of infestation (period and density) by C. bipunctata, and since C. bipunctata density is quite low until mid-July, the earlier seeding of the second crop and the use of MWES-resistant varieties is an effective way to avoid damage from MWES. This leafhopper shows a unique relationship between plant and herbivores because MWES induction by adult C. bipunctata helps improve the development of their offspring through the accumulation of amino acids on the host plant.