Seoul's Lovebug Swarms Fuel Debate Over Urban Heat and Pest Control

A Summer Nuisance With an Ecological Role

Seoul is facing a summer surge of lovebugs in 2025, with swarms covering hiking trails, parks and residential neighborhoods across the metropolitan area. Complaints to municipal offices rose from 4,418 in 2023 to more than 9,296 in 2024, more than doubling as residents demanded action against insects that cling to clothing, gather on vehicles and enter homes.

At Gyeyangsan Mountain in Incheon, west of Seoul, viral images and videos have shown observation decks and paths carpeted in black by the insects. Some districts have received more than 100 reports in a single day. The scale of the outbreak has turned a seasonal annoyance into a dispute about public comfort, environmental protection and how cities should manage changes in their ecosystems.

The insects, scientifically known as Plecia longiforceps, do not bite, sting or transmit diseases. Their larvae help break down decaying organic matter, while adults pollinate flowers. Those benefits complicate demands for widespread spraying: a response aimed at removing the swarms could also harm other insects and the environments they support.

Climate change, heat retained by buildings and roads, and development around mountain habitats are central to explanations for the surge. Researchers are also examining how the insects adapt to an environment where natural enemies may initially be scarce.

As of July 2, 2025, Seoul's response combines public information, practical measures to reduce contact with the insects and research into more targeted controls. The immediate challenge is to make daily life more comfortable while avoiding damage from indiscriminate pesticide use.

What Are Lovebugs?

Lovebugs are a species of march fly, recognizable by the way mating pairs remain attached at the abdomen while flying. They can stay connected for several days, a behavior that gives them their familiar name.

Males typically die after three to four days. Females live for about a week and lay hundreds of eggs in moist soil rich in organic matter before dying. Their brief adult lives can still create a substantial disturbance when large numbers appear together.

Plecia longiforceps is originally native to subtropical parts of southeastern China, Taiwan and Japan's Ryukyu Islands. The species was first scientifically identified in South Korea during a major outbreak in 2022. Its numbers have since grown sharply, particularly around the Seoul metropolitan area.

The insects' harmlessness offers limited comfort to people surrounded by them. A Seoul Institute survey found that 86% of residents regarded lovebugs as pests, ranking them just behind cockroaches and bedbugs in public revulsion. Their status in everyday life is shaped by their overwhelming presence, even though they do not present the biting or disease risks associated with some other insects.

Why Is the Outbreak Concentrated Around Seoul?

Rising global temperatures have made Seoul more hospitable to insects associated with warmer, more humid regions. Climate change can allow species to move north into places where conditions were previously less suitable.

Seoul also has an urban heat island effect. Concrete and asphalt absorb heat and release it later, leaving built areas warmer than the surrounding countryside. This local warming can create favorable conditions for lovebugs within a region that would otherwise be cooler.

Shin Seung-gwan, a biologist at Seoul National University, considers that local heat an important part of the explanation for the insects' concentration around the capital rather than in South Korea's naturally warmer southern regions. He said:

I think, more than climate change, it may have more to do with the urban heat island effect [occurring when a city has much warmer temperatures than the surrounding area]. But the scale of the current population surge certainly isn't normal and is something that warrants further observation.

Urban expansion is changing the insects' habitat as well. Development around mountains disrupts local ecosystems and can create new breeding grounds. As construction spreads into formerly wild areas, it can also provide the moist environments rich in organic material that lovebug larvae need.

From a 2022 Outbreak to Thousands of Complaints

Lovebugs have become an increasingly visible problem over several summers. The complaint figures show how quickly pressure on local authorities has grown, while the images from Incheon show the scale that concentrations can reach in popular outdoor spaces.

The main developments leading to the current debate are:

• 2022: Plecia longiforceps was first scientifically identified in South Korea during a major outbreak.
• 2023: Municipal offices received 4,418 complaints about lovebugs.
• 2024: Complaints rose to more than 9,296, more than twice the 2023 figure.
• Summer 2025: Large swarms affected the Seoul metropolitan area, including trails and observation decks at Gyeyangsan Mountain in Incheon.

Residents encounter the insects beyond parks and mountains. They have reported finding them in homes, cars and on public transportation. Hikers wave their arms to clear swarms from their path, while photographs and videos shared on social media have brought the experience to a wider audience.

Some people have responded with humor. One YouTuber cooked and ate a "lovebug burger," describing its taste as "like trees." For other residents, the repeated encounters have created frustration and a sense that authorities are not doing enough.

Why Seoul Is Resisting Widespread Spraying

Seoul's government has resisted calls to officially designate lovebugs as pests, a step that would allow widespread chemical extermination. City authorities instead stress the insects' ecological benefits and warn about the consequences of broad pesticide use.

Chemical sprays can kill beneficial insects and pollinators alongside lovebugs. They can also threaten human health. The management problem therefore extends beyond how quickly a treatment clears a path or building: officials must also consider what else it affects.

Lovebug larvae contribute to soil health by breaking down decaying organic matter. Adults assist with pollination. Removing large numbers through broad chemical treatment could affect those functions while exposing other organisms to the same chemicals.

Residents calling for stronger action are responding to a real disruption in daily life. Even without bites or disease, large swarms can make outdoor spaces unpleasant and leave people uncomfortable in their own homes. That psychological burden helps explain why official assurances about harmlessness have not ended public demands for control.

Environmental specialists and city officials argue that spraying alone is too simple an answer to a problem involving both nuisance and ecological value. Seoul's public information campaigns have tried to explain that balance while encouraging measures that reduce contact with the insects.

What Residents Can Do Now

Officials recommend several practical responses, most of which avoid chemical treatment. These measures focus on removing insects from surfaces, reducing their attraction to buildings and managing those that get indoors.

• Spray water to remove lovebugs from surfaces.
• Install light traps and sticky pads around outdoor lighting, where the insects gather.
• Wear dark clothing outdoors because lovebugs are attracted to bright colors.
• Use a vacuum cleaner or household insect spray for insects inside the home.
• Close curtains to block light that can attract insects indoors.

Light is an important part of this advice because lovebugs are drawn to bright sources. Blocking indoor light with curtains and managing insects around outdoor fixtures address places where people and swarms repeatedly meet.

The recommendation to use household insect spray indoors sits alongside the city's opposition to widespread chemical extermination. The approach distinguishes treatment of an indoor infestation from broad spraying across outdoor habitats, where many other organisms could be exposed.

Natural Predators and More Targeted Treatments

Government scientists are developing fungal pesticides aimed specifically at lovebug larvae. The purpose is to control the insects while limiting damage to other organisms. The treatment remains under development, and no deployment date has been given.

Natural controls are also emerging. Magpies and sparrows are learning to prey on lovebugs, contributing to noticeable declines in affected areas. Predators can become part of the response as an unfamiliar insect becomes a food source within its new environment.

Shin Seung-gwan, the Seoul National University biologist, described how an initial population surge can change as other organisms adapt to it:

In the process of organisms adapting to a new environment, it's common for their populations to explode in the absence of natural enemies. But over time, those natural enemies or pathogens appear, and their population density decreases.

A similar pattern has been observed with the spotted lanternfly. Its numbers eventually stabilized after the arrival of a parasitic wasp that attacks its eggs. The example helps explain why researchers are watching predators and disease organisms alongside the lovebugs themselves.

A Local Outbreak Within a Wider Ecological Shift

Researchers from Pusan National University and the Seoul Institute have highlighted the infestation as evidence of declining biodiversity and unintended effects of rapid urbanization. The mass appearance and death of adult lovebugs in urban and natural areas is a visible part of those changes.

Biodiversity means the variety of living things in an environment. Seoul's outbreak has focused attention on how development and changing temperatures can alter the relationships among insects, their habitats and the organisms that feed on them.

Scientists around the world are documenting insects and other species moving north as a consequence of climate change. In the United States, the Lone Star tick has expanded its range, bringing new health risks to areas previously unaffected.

Lovebugs present a different immediate problem because they do not bite, sting or transmit diseases. Their spread still shows how changing species distributions can disrupt ecosystems and create new responsibilities for urban authorities. In Seoul, those responsibilities include managing swarms in shared spaces while considering the insects' role in soil health and pollination.

How Pest Control and City Planning Could Change

Specialists advocate Integrated Pest Management, or IPM, as an approach to the outbreak. It combines biological controls, such as encouraging natural predators, with practices such as removing breeding grounds and using pesticides sparingly and selectively.

The approach aims to manage insect populations effectively while limiting environmental damage. For Seoul, it brings together several responses already under discussion: practical action around buildings, observation of natural predators and research into treatments aimed at lovebug larvae.

Urban planners are also being urged to consider how development affects ecosystems. More green space, reflective building materials and better landscaping can help reduce the urban heat island effect, making cities less attractive to invasive species. Buildings and public spaces can also be designed to reduce insect attractants, including bright outdoor lighting.

Citizen science initiatives, in which residents help monitor insect populations and report outbreaks, are gaining traction as a way to collect useful information and improve public awareness. Reports from affected neighborhoods can help track where the insects are appearing as researchers examine the conditions behind the surge.

Seoul's experience brings those tasks together: relieve the immediate nuisance, understand the changing environment and choose controls that account for other living things. For residents, the most concrete measures remain managing light, removing insects from surfaces and dealing with indoor infestations while authorities investigate more targeted options.

Key Points

• Lovebug complaints rose from 4,418 in 2023 to more than 9,296 in 2024, with large swarms continuing around Seoul in summer 2025.
• Plecia longiforceps does not bite, sting or transmit diseases, but its overwhelming presence has caused widespread discomfort.
• Climate change, urban heat and development around natural habitats are central explanations for the surge.
• Seoul is resisting widespread chemical extermination and recommending practical measures including water spraying, traps, dark clothing and curtains.
• Lovebug larvae break down organic matter, while adults help pollinate flowers.
• Birds are beginning to prey on the insects, and government scientists are developing fungal pesticides aimed at larvae.
• Integrated Pest Management, changes to urban planning and resident monitoring are among the approaches being promoted.