Citronella is an oil with a sharp, lemon-like smell, used to keep insects away — in candles, sprays, lotions, and those outdoor lamps people light in summer. It is pressed from a tall grass, not from the citron fruit, though the name borrowed the “lemon” idea because of the smell. Though actually, the grass in the kitchen (the one you put in soup) and the grass in the mosquito oil are close relatives, but they are not always the same plant, and citronella on a bottle usually means the insect-keeping oil, not a cooking herb. It does not kill insects so much as push them off; on a very buggy night it helps, it does not work magic.

香茅油（驅蟲用；廚房裡的香茅是近親，但這詞多半指防蚊的油）