Are Cockroaches from Seoullo Spreading to Nearby Areas? "No Way to Verify Population Size"

A video showing a swarm of cockroaches appearing at 'Seoullo 7017' near Seoul Station recently went viral on social media.

Some raised claims that the cockroach population is increasing as pests from Seoullo 7017 spread beyond the surrounding area to nearby apartment complexes.

It is true that cockroaches appeared at Seoullo 7017, as shown in the video circulating on social media.

Cockroaches are pests known for their remarkable survival skills and rapid reproduction rates.

A single female can lay more than 40 eggs at a time and multiply into hundreds in a year.

In addition, their thin, flexible bodies allow them to easily hide in tiny crevices, making them hard to detect.

In particular, hot and humid conditions significantly affect the growth and activity of cockroaches.

The appearance of cockroaches at Seoullo 7017 is also analyzed as the result of such environmental factors.

Yang Young-chul, a professor in the Department of Environmental Health and Safety at Eulji University and an expert on sanitary pests, said in a phone call, "Humidity is important for cockroach habitats, and because Seoullo 7017 has flower beds that are watered, it created a favorable environment for cockroaches to live." He added, "As the location became widely known as a walking area, food dropped by visitors also affected the cockroaches' feeding habits, which likely led to an increase in their numbers."

However, experts say that an increase in cockroaches at Seoullo 7017 does not necessarily confirm whether Seoul's overall cockroach population has increased.

Jeon Kye-nam, a senior researcher at the Korea Pest Control Association, said, "To determine whether the population has increased, collections must be conducted at the same location over several years and scientifically analyzed based on that, but no such data exists."

Kim Dong-keun, head of the Environmental Ecology Research Institute at Sahmyook University, also explained, "There is no data showing how many there were in the past, and just because there are many in one area does not mean there are many in other areas, making it difficult to judge population changes."

An official from the Seoul Metropolitan Government's Infectious Disease Control Team also stated, "After checking with several experts, there appears to be no research data tracking Seoul's cockroach population, so it is impossible to know whether numbers have recently increased."

Although there is no objective data to confirm the population size, some interpretations suggest that the number of cockroaches in Seoul may have increased based on circumstantial factors.

This is based on the recent rise in civil complaints submitted to district offices across Seoul requesting pest control due to cockroach sightings.

According to data on pest complaint submissions and processing received from the Seoul Metropolitan Government by Representative Kim Wee-sang of the People Power Party, a member of the National Assembly's Climate, Energy, Environment and Labor Committee, the number of cockroach-related complaints received and handled in Seoul from January – June this year was 6,158 cases.

This accounts for 52.2% of last year's total annual complaints received and processed (11,789 cases).


Considering that pest-related complaints tend to be concentrated in the summer months, the total number of complaints this year is likely to be significantly higher than last year.

According to the data, cockroach-related complaints received and handled in Seoul have grown rapidly over recent years, with 2,379 cases in 2021, 3,905 in 2022, 5,470 in 2023, 7,241 in 2024, and 11,789 in 2025.

However, some experts point out that the recent increase in complaints may be influenced by increased movement of people following the end of the COVID-19 pandemic.

This is because during the spread of COVID-19, people refrained from going out, leading to fewer opportunities to see cockroaches outdoors.

Experts also diagnose that even if the cockroach population in Seoul has increased, it is difficult to attribute it to the cockroaches at Seoullo 7017.

Professor Yang analyzed, "Although cockroaches are insects with well-developed wings, even if they fly far, it is only about 15 to 20 meters." He added, "It is impossible for them to fly around and spread across all of Seoul like lovebugs."

A Seoul official also said, "Everyone considers such an interpretation nonsense, and experts would likely agree."

Why, then, are claims emerging online that cockroaches are appearing more frequently than in the past? Some point to higher overall temperatures caused by climate change and other factors.

However, experts agreed that the attention drawn to the video of cockroaches at Seoullo 7017 could be a major factor.

They explained that once people become aware of the presence of cockroaches, they suddenly notice them more, making it feel as if there are more around.

Researcher Jeon Kye-nam said, "While climate change may have an effect (as mentioned on social media), as the cockroach situation at Seoullo 7017 became an issue, provocative videos by YouTubers followed. Consequently, people who watched these videos or heard about them seem to have paid closer attention."

Director Kim Dong-keun also stated, "Lovebugs have also drawn greater public interest after being exposed in the media," adding, "There is an impact from being exposed on platforms like YouTube."

The ongoing high temperatures of summer combined with the monsoon season have also made them more noticeable recently.

Professor Yang Young-chul said, "With heavy rain recently falling in the metropolitan area, cockroaches living around sewers and manholes seem to have emerged en masse.

Also, in the metropolitan area, sewers are often cleaned right before the monsoon season to ensure smooth drainage. The vibrations generated during cleaning likely cause many cockroaches to escape and move elsewhere, making them more visible to people."

The creation of green spaces, such as parks throughout Seoul, is also analyzed to have had an effect.

A Seoul official said, "During heatwaves or heavy rain, cockroaches living in sewer pipes often burst out, and the creation of many green spaces in the city center has also created favorable living conditions for cockroaches."

Director Kim also noted, "Urban green spaces themselves serve as habitats for insects.

However, when bugs appear, people dislike them, leading to pest control efforts. In the end, only resilient species that have developed resistance to insecticides survive, and those are cockroaches," explaining why cockroaches are being spotted more frequently in urban areas.


Cockroaches are pests that pose a serious threat to hygiene and health, going beyond mere unpleasantness.

According to a news card recently published by the Seoul Metropolitan Government's Citizen Health Bureau, cockroaches spread various infectious diseases, including food poisoning, cholera, and typhoid fever.

They also trigger asthma and chronic rhinitis.

According to the Korea Disease Control and Prevention Agency's National Health Information Portal, adults and children exposed to cockroaches—along with fumes and vapors from gasoline or biofuels, and mold—show higher rates of asthma.

The Korea Disease Control and Prevention Agency also identified cockroaches as one of the causes of perennial allergic rhinitis, where symptoms persist year-round.

For this reason, some autonomous districts in Seoul, such as Geumcheon-gu, Seongdong-gu, and Jungnang-gu, define pests like flies and cockroaches—which can directly or indirectly transmit pathogens and cause harm—as "sanitary pests" in their local ordinances.

Cockroaches are also the most avoided pest among the general public.

According to a report titled "The Spread of Harmful Urban Pests in Seoul and Countermeasures," published by the Seoul Institute in April last year, a survey of 1,000 Seoul residents on their perceptions of harmful urban pests showed that cockroaches ranked highest among pests people found disgusting or frightening just to look at (66%), followed by bedbugs (60.1%), lovebugs (42.6%), and mosquitoes (39.2%).

In this regard, methods to eradicate cockroaches appearing indoors are also a topic many people are curious about.

The Seoul Metropolitan Government advises that a fundamental approach is required, including blocking entry points and managing habitats.

In terms of habitat management, food waste should be kept sealed, and foreign substances, food scraps around the kitchen, and drainage pipes should be properly maintained.

Since pipes, drains, windows, kitchen hoods, and ventilation vents are primary entry points, screens should be installed at these locations to seal off gaps.

There are also posts online claiming that using specific products is highly effective.

However, even within the same space, different types of cockroaches require different pesticides and dosage amounts, making it better to seek professional help.

This is because it is difficult for individuals to accurately identify the species or entry route, and using the wrong pesticide can lead to increased pest resistance.

While apartment complexes are obligated to conduct self-disinfection, when pests are spotted in public places, reporting them to the local autonomous district health center will initiate pest control work.

(Photo: Yonhap News)
※ Please note: This article was translated by AI and may contain errors.