As Seoul continues to experience increasingly extreme summer temperatures, an unexpected consequence is emerging: a dramatic drop in mosquito populations during the hottest months of the year. Data from the Seoul Metropolitan Government reveals that the number of mosquitoes trapped in the capital has plunged by more than half over the past decade, a trend experts attribute not only to advanced pest control efforts but also to weather patterns that are becoming too harsh even for these resilient insects.
In June 2025, mosquito monitoring in Seoul captured 62,351 mosquitoes — a steep 56% decrease compared to June 2015, when nearly 140,000 were recorded. The latest figure also shows a year-on-year decline from June 2024, when 68,462 mosquitoes were caught. During an intense three-day period from June 17 to 19, when daytime highs soared to nearly 37°C (98.6°F), just 6,233 mosquitoes were collected across 55 monitoring sites — a daily average of about 2,000. That’s down from a daily average of 2,590 mosquitoes recorded during the same period last year.
Authorities say the downturn in mosquito numbers is partially due to high-tech pest management strategies. Seoul has implemented a wide range of mosquito control technologies, including drones that spray insecticides in hard-to-reach areas such as urban parks, and LED traps that lure insects using light. Automatic repellent dispensers and specialized mosquito traps have also been deployed across districts like Gangnam and Nowon, helping reduce local populations without widespread use of chemical fogging.
However, technological interventions tell only part of the story. According to entomologists and climate scientists, the overwhelming heat and shrinking monsoon seasons are having a far more profound effect. Professor Park Hyeon-cheol of Pusan National University’s Department of Life Science and Environmental Biochemistry explained that mosquitoes typically thrive in environments where the temperature ranges between 25°C and 28°C (77°F to 82°F). Once temperatures exceed 32°C (89.6°F), their survival becomes difficult, and prolonged exposure to temperatures near 37°C can be fatal.
The issue is compounded by changing rainfall patterns. While Seoul’s monsoon season had not officially ended by mid-July, areas like Jeju Island and South Korea’s southern regions saw their shortest monsoon durations in years — just 15 and 13 days respectively, less than half of what was recorded a decade ago. These shortened and often drier monsoons mean fewer puddles and stagnant water pools, which are essential for mosquito breeding.
Even when rain does fall, the now-frequent intense downpours tend to wash away mosquito eggs and larvae before they can mature. “Heavy rain may seem like an ideal environment for mosquito breeding,” Park noted, “but when the rain falls too fast and hard, it destroys the very conditions mosquitoes need to reproduce.”
While the summer lull in mosquito activity might come as welcome news to Seoul’s residents, experts caution that this could lead to a shift in the mosquito season rather than its elimination. Park warned that cooler temperatures beginning in September could bring a resurgence in mosquito numbers, extending their presence well into the fall and even early winter. “What we’re likely to see is a temporal shift — fewer mosquitoes in summer, but potentially more in the months that follow.”
This trend also raises new public health concerns. Mosquito-borne illnesses, while relatively rare in South Korea, are still a risk. Warmer falls and milder winters could allow mosquitoes to stay active for longer periods, increasing the chance of disease transmission. The Korea Disease Control and Prevention Agency (KDCA) has been monitoring changes in vector populations and encouraging municipalities to adapt their pest control calendars accordingly.
As climate change continues to reshape ecosystems around the world, even something as small as a mosquito serves as a vivid indicator of the broader environmental transformations underway. Seoul’s experience this summer is just one example of how cities must rapidly adjust not only to hotter temperatures but also to shifting patterns in public health, pest management, and urban planning.
Whether the capital can maintain its declining mosquito counts in the long term will depend not only on weather but also on sustained investment in public health infrastructure and adaptation strategies.
