Chills After Visiting the 'Hot Place' Seongsu-dong... Invasion of Oriental Mayflies

Dongyang Harusari Appears at Night in Seongsu-dong Area
Mouth Degenerated, Does Not Bite... No Infectious Disease Concern
"Responding by Minimizing Light Brightness and Installing Screens"

Recently, large swarms of the giant mayfly known as 'Dongyang Harusari' have appeared every night in the Seongsu-dong area, causing discomfort among residents.

According to Seongdong District Office on the 12th, Dongyang Harusari, which had rarely appeared in Seongdong-gu for several years, has appeared in large numbers along the Han River this year.

Dongyang Harusari is an insect of the mayfly family that only inhabits clean water of grade 2 or higher. It mainly appears between May and June in areas such as Gangdong, Gwangjin, Songpa, and Seongdong districts in Seoul, as well as Yangpyeong, Namyangju, and Hanam in Gyeonggi Province, and naturally dies within five days.

Oriental mayfly stuck on the convenience store window
[Photo by Namyangju City]

Dongyang Harusari have degenerated mouths and do not bite people, so the likelihood of infectious diseases caused by viruses or bacteria is low.

However, Dongyang Harusari tend to swarm toward bright lights, which causes disgust among residents. Especially at night, they cling densely to windows and lights, sometimes causing damage to business operations.

Jung Won-oh, mayor of Seongdong District, stated on social media (SNS), "The Han River basin is designated as a water source protection area," adding, "It is indeed difficult to indiscriminately spray insecticides."

Swarming on Windows... How to Deal with Dongyang Harusari!

How to Deal with Oriental Mayflies [Image Source=Seongdong-gu Office Blog]

Seongdong District Office shared guidelines for residents suffering from Dongyang Harusari, saying, "If you encounter a swarm of Dongyang Harusari, do not be startled and respond as follows."

Since Dongyang Harusari are attracted to strong lights, it is recommended to lower the brightness of lights after 8 p.m. Replacing white lights with yellow-toned lights or sodium lamps can also be effective.

To prevent them from entering indoors, check the gaps around doors. Installing mosquito nets or screens can further enhance effectiveness.

If Dongyang Harusari have already attached to the exterior walls or windows of buildings, they can be removed using water. Using a spray bottle or hose makes removal easy.

In addition, Seongdong District has operated 353 eco-friendly pest repellers along walking paths by the Han River and Jungnangcheon Stream and strengthened pest control in grassy areas to minimize residents' inconvenience. A rapid response pest control team is also in operation for swift handling of complaints.

Netizens who reviewed the response guidelines commented, "I think I need to wear a mask to avoid them getting into my mouth," and "They don't harm us, but they are creepy and scary."