TAIPEI (Taiwan News) — Lychee is an important agricultural product in Kaohsiung City, and farmers are now using green lighting at night to ward off a key pest: the lychee moth.

The green light has been found effective in suppressing moth activity during nighttime hours. Testing is set to expand in May, which marks the beginning of the lychee harvest season, per CNA.

Kaohsiung is Taiwan’s largest producer of the prized jade purse lychee (玉荷包), cultivating the fruit across 2,340 hectares. The city’s annual production is estimated at 9,653 metric tonnes, with an output value of NT$1.6 billion (US$43.9 million).

While consumers enjoy the sweet and juicy fruit, the presence of a nearly transparent moth larva inside the fruit can be unsettling. The larva, which is the same color as lychee flesh, can frighten consumers and render farmers' crops unsellable.

Kaohsiung’s Department of Agriculture (DOA) issued a press release on Monday noting that lychee moth larvae damage fruit, cause premature fruit drop, and reduce commercial value. It also warned that climate change has worsened pest control challenges by accelerating pest breeding cycles.

To address the issue, the DOA commissioned National Chiayi University to conduct research beginning in 2021. The research showed that moth populations increase rapidly as lychee trees begin to flower and bear fruit.

The study found that green light at night inhibits moth activity, thereby reducing the need for pesticide use and increasing production.

According to the DOA, green lights could replace two laborers typically needed for daily pesticide application—at a cost of NT$4,000 (US$123) per day—while also cutting down on the need to spray pesticides four to six times a year.

Test results showed that green lighting could reduce moth damage to less than 2% of the crop. The department added that the cost of installing the green lighting and power system could be recovered within a year.