Different species of overseas pests are destroying local crops: (from left) the Lycorma delicatula, Metcalfa pruinosa, blueberry gall midge and the Formosan subterranean termite.[JoongAng Ilbo]

Kim Young-gyeom, a 62-year-old farmer who grows ginseng in Anseong City in Gyeonggi, recently discovered whitish, frost-like spots on the leaves of his crop.

Then he realized the leaves were dying, and he checked the spots again. They weren’t spots: They were insects feasting off his crop. Its name was Metcalfa pruinosa, or the flatid planthopper.

The bugs, which are believed to have come from Europe or the U.S., were first detected in Mount Umyeon, southern Seoul, in 2009.

Now, they can be found in 27 cities and counties throughout Korea, destroying economically important plants and crops.

The pest feeds on sap to extract the sugar. The species is known for passing bacteria and fungal infections to the crops. Summer is their season.

Researchers say the species has spread across Korea with surprising speed.

“Metcalfa pruinosa like car headlights. It seems they moved out through the country following the lights of cars,” said Lee Gwan-seok, a researcher at the National Academy of Agricultural Science, a state-funded research institute under the Rural Development Administration.

The regions who are now home to the insects - Suwon, Yongin and Anseong - are connected by the Gyeongbu Expressway.

“Many experts expected the foreign insects to disappear due to the different climate but most of them, on the contrary, spread at a quick pace,” said Choi Moon-bo, a biology professor at Yeungnam University.

Due to the effect Metcalfa pruinosa has on crops, Korea categorizes it as “harmful pest.”

“America and some overseas countries count Metcalfa pruinosa as a general insect,” said Kim Gwang-ho, a researcher from National Academy of Agricultural Science.

“But it causes a yield loss in Korea, which led the country to categorize it as a pest.”

The bug is but one example of foreign pests taking a toll on Korea’s farmers.

The blueberry gall midge, which is from the United States, is causing substantial losses in blueberry farms. The midge was first found in southern Gyeonggi, southern Chungcheong and northern Gyeongsang after finding their ways into Korea through imported seedlings. Now, they are affecting northern Gyeonggi as well.

Formosan subterranean termites from Japan and Taiwan have caused damage to national heritage sites made of wood. Old wooden temples including Beopju Temple in Boeun County, North Chungcheong, and Beomeo Temple in Busan have been infested.

“I can’t properly grow crops because of different kinds of foreign insects,” said Lee Il-seok, 71, a peach farmer in Yeongdong County, North Chungcheong.

As with the blueberry gall midge, most exotic pests get into Korea through shipped goods.

The Animal and Plant Quarantine Agency found that the number of foreign pests found during quarantine inspections last year amounted to 624 species and 9,824 cases. In the first half of this year, 442 species and 4,117 cases were discovered.

BY CHOE MO-RAN, PARK EUN-JEE [ejpark@joongang.co.kr]