Café and restaurants in downtown areas have to close their door after sun went down due to swarms of Ephemera orientalis

A sign of Oriental Haru-sal is displayed in the front window of a shop in Seongdong-gu, Seoul, where Shin Sang-chul works, on Wednesday. Contributed by readers

On May 12, at the intersection in front of Ttukdo Market in Seongsu-dong, Seoul, streetlights turned on as usual as the sun went down and it became dark. A group of men in their 20s waited at the crosswalk for the light to change to green. One of the men saw objects coming down from the sky and pointed them in surprise. “Oh my god, can you see that?” he said. As if it was snowing heavily, something was falling down from the sky. The group looked in the direction he pointed. They ran away, screaming in unison, "Aargh!"

It was a swarm of “Ephemera orientalis” that had fallen from the sky. Their main targets are store signs and white walls illuminated with LED lights.

Since last week, swarms of Ephemera orientalis have been appearing in downtown areas. Self-employed people who met in Seongsu-dong complained of difficulties, saying that their business was disrupted by the bugs.

"There were thousands of Ephemera orientalis at the entrance of the store last Thursday and Friday,” said Shin Sang-cheol (24), who works as a manager at a restaurant in Seongsu-dong. “It was so disgusting that all the people in the store left and no one came in,” he sighed. Shin's restaurant has 14 tables. On that day, as the bugs began to appear in the window, the customers who were sitting at the tables began to ask for the bill one by one.

At around 6:30 p.m. on the same day, Lee Sang-mi (45), who runs a cafe in the same neighborhood, was preparing to close her shop. “Since last week, if I left the door open, the bugs would stick to everything, including foods and the menu,” she said. “I can't ventilate the cafe, and customers cannot come in as they are all over the doorknob.

As the situation has become more serious, there have been calls for the local government to take action. The Seongdong-gu Office distributed a notice to residents on the 7th when Ephemera orientalis were first observed on the previous day. The solution proposed by the district office was to spray water and reduce the brightness of lights.

“I turned off the signboard and turned down the lights as the district office instructed,” said Mr. A (30), a self-employed business owner, “but it was useless because the bugs were snowing like crazy.” He added, “When I closed the door and turned off the lights, people thought the store was closed and didn't even come in.”

Ms. Lee, who was killing the bugs that entered her store with an electric swatter, also expressed frustration, saying, "The district office told us to spray water with a sprayer, but does it make sense to spray water one by one to thousands of bugs?" As soon as she finished talking to the reporter, she closed the store and turned off the lights.

Since the 7th, the Seongdong-gu Office has been mobilizing two teams of quarantine squads to eliminate the bugs. Kim Jin-woo, head of the Disease Prevention and Control Division in the Seongdong-gu Office, said, “The source of Ephemera orientalis is the Han River, but it is difficult to control it with chemicals. At present, there is no other way but physical removal." He added, “It mainly appears in areas with many shopping centers along the river, so we are asking them to turn off their LED signs after business hours.” The district office will soon mobilize private quarantine companies to carry out disinfection work.

Ephemera orientalis live along rivers with grade 2 or higher. Their mouths have degenerated and they do not bite or transmit infectious diseases. However, an Ephemera orientalis usually lays 2,000 to 3,000 eggs. “Once they appear, they are so numerous that they are stepped on every time you walk down the street,” said Uhm Hoon-sik, a senior researcher at the Korea Pest Control Association. “Considering the number of self-employed people and who are affected by the bugs in downtown areas, we should also consider conducting disinfection using chemicals there.”

Yang Young-chul, a professor of health, environment and safety at Eulji University, said, "When managing pests or vectors, quarantine is important, but it is difficult to take preventive measures against the source, but in the case of Ephemera orientalis, it is difficult to control because the Han River is the base for the outbreak of the bugs and also it is a water supply protection area and the scope is wide." He added, "The lights attract males, but in reality, the lights in downtown areas cannot be reduced. I recommend using air curtains to prevent them from entering stores and using air inhalers to physically remove them.”

Yang also said, “Recently, due to frequent rains, the larvae in the upper stream of the Han River, such as Namyangju, have been floating to the downstream, expanding the affected areas. I suspect that the cause is basically the disappearance of native fish, which are the natural enemies of the larvae in the Han River.”

※This article has undergone review by a professional translator after being translated by an AI translation tool.