Jacobiasca formosana, also known as the small green leafhopper, tea green leafhopper, or tea jassid, is a species of cicada that feeds on tea bushes and cotton plants. In the past, these cicadas were considered pests and were actively controlled. However, in recent years, they have been intentionally used to produce certain types of oolong tea, including Oriental Beauty and Guifei oolong.
When the cicadas feed on the tea leaves, the plant secretes an attractant in an attempt to draw in the cicadas’ natural predators, such as spiders. This changes the chemical composition of the tea leaves and, if processed correctly, can result in a tea with a distinctive honey-like scent. It is important to note that this process only works when the tea is grown naturally and without the use of pesticides.
It is known by several different names in different languages: in Mandarin Chinese, it is called 茶小綠葉蟬 (chá xiǎo lǜ yèchán) or 小綠浮塵子 (xiǎo lǜ fúchénzǐ); in Siyen Hakka, it is called 著涎 (Zhe xián), 著蜒 (Zhe yán), or 著煙 (Zhe yān); and in Taiwanese, it is referred to as 浮塵仔 (phû-tîn-á), 蜒仔 (iân-á), 蝝仔 (iân-á), 烟仔 (ian-á), 趙烟 (tiō-ian), 跳仔 (tiô-á), or 青仔 (chhiⁿ-á).
It is worth noting that other insects, such as Empoasca vitis (the false-eye leafhopper) and Empoasca flavescens (the lotus mist small green leafhopper), are also known as tea green leafhoppers or small green leafhoppers, which can lead to confusion.