說明/ 體長4.3–4.6 公分，雄蟲複眼黑色或黑褐色，胸部黑色，胸側有2 條不明顯黃白色斜斑。腹部黑色，腹部近前方第3–4 節有寬大的白斑，如上圖。翅透明，翅端有褐色斑，翅痣黑色，後翅基具黑褐色斑。雌蟲腹部第3–4 節黃色，本種以雌蟲命名。分布於平地至低海拔地區，多出現於湖泊、池塘等水域，族群數量多，成蟲主要出現於5 月到9 月。喜愛靜水環境，雄蟲常見於水面互相追逐，飛行速度很快。雌蟲數量較少，交尾後常於水面的枝條或浮木上產卵。（黃予恩攝）
It is about 4.3-4.6 cm in length. The male’s compound eyes are black or blackish-brown; the thorax is black with two indistinct yellowish-white marks on the sides. The abdomen is black, with wide, white spots near the third to the fourth segments, as seen in the above picture. The wings are transparent with brown marks on the margin and black stigmas. The hindwings have blackish-brown marks. The third to the fourth segments of the female’s abdomen are yellow, giving it its Chinese name. It is distributed across plains and low altitude areas, often appearing around lakes, ponds, and such areas with a large population. The adults appear between May and September. It prefers still waters. The males can often be seen chasing each other over water, flying at a fast speed. The females are smaller in number and lay eggs on the branches near the surface of water or driftwood. (Photo courtesy of Huang Yu-en)