Large-Scale Pest Control Measures Effective in Reducing Lovebug Population

"It appears that the large-scale pest control measures have certainly been effective. Following the mass outbreak last year, increased competition among the population has also naturally regulated their density," said Kim Dong-geon, head of the Environmental Ecology Research Institute at Sahmyook University and an expert on the so-called lovebug, during an interview at his office in Nowon-gu, Seoul, on July 6.

The lovebug, scientifically known as Plecia longirostris, caused significant public aversion last year as it swarmed in massive numbers, blanketing the sky and ground in areas such as Baegnyeonsan Mountain in Seoul and Gyeyangsan Mountain in Incheon.

Local governments, including the Seoul Metropolitan Government and Incheon Metropolitan City, launched pest control operations in collaboration with the National Institute of Biological Resources and Sahmyook University.

The Environmental Ecology Research Institute at Sahmyook University conducts research on the characteristics, habitats, and mitigation strategies for pests, including the lovebug.

The research team, led by Professor Kim, has been studying the causes of the lovebug mass outbreaks and potential control measures since 2024. They have been working with the Ministry of Environment and local governments to implement control measures using Bacillus thuringiensis israelensis (BTI), a microbial pesticide.

BTI is a bacterium found in soil that has been used to eliminate mosquito larvae.

"Experiments with BTI on the black-legged march fly, which belongs to the same Bibionidae family as the lovebug, showed that 98 percent of the larvae died within 48 hours," Professor Kim said. "We determined that it would be effective against lovebugs, which are also in the order Diptera, and have been focusing our control efforts on Gyeyangsan, Baegnyeonsan, and Buramsan mountains since last year."

BTI control measures target larvae rather than adults.

This is because the BTI toxin acts on the alkaline midgut of fly larvae.

Professor Kim pointed out, "If you wait until after the lovebugs have swarmed and public complaints have increased to start control measures, it is already too late."

Since September last year, the research team has been monitoring the density of lovebug larvae every month in 44 cities, counties, and districts across the country, including Gyeyangsan Mountain, as well as areas in Seoul, Gyeonggi, and Gangwon provinces.

They have applied BTI control measures in areas where larvae were discovered or where their presence was confirmed through signs such as molting, and have also installed traps to suppress the adult population.

As a result of these efforts, the number of lovebugs reported this year has decreased compared to last year.

"We are analyzing the effects by comparing the number of adults in areas where BTI was applied versus areas where it was not," Professor Kim said. "Preliminary results show that the control measures are clearly effective in the treated areas."

Professor Kim advised that consistent control efforts for lovebugs are necessary.

This is because research has confirmed that the lovebug is an invasive species introduced from regions such as the Shandong Peninsula in China.

"There is a record of their first appearance in Korea in 2015, and it appears they were introduced through container ships traveling between China and Korea and were first discovered in Incheon," Professor Kim explained. "Since then, they have found favorable environments to lay eggs and multiply, leading to mass outbreaks in Eunpyeong-gu, Seoul, in 2022, and on Bukhansan Mountain in 2023."

He analyzed that since it is difficult to predict the impact of an invasive species on the domestic ecosystem, their population must be continuously managed.

Lovebugs mainly inhabit areas with high humidity and layers of leaf mold formed by decaying fallen leaves.

"Korea has a lot of leaf mold, which makes it a good habitat, and there are almost no natural predators in the country, so there is a possibility that they could spread rapidly without density limits," Professor Kim said.

While some have claimed that lovebugs are beneficial insects that do not bite humans and help with pollination, Professor Kim pointed out that this is misinformation.

"The claim that they are beneficial is a distortion," he said. "Invasive species should not be viewed through the lens of being beneficial or harmful. Because we do not know what impact they will have on the domestic ecosystem, we must control their density to prevent mass outbreaks."

He added, "It is true that lovebugs are anthophilous insects that visit flowers, but they are not pollinators that transfer pollen. If their carcasses accumulate, it can lead to secondary hygiene problems, such as attracting cockroaches or rats, which could result in greater economic costs."

The range of the lovebug's spread in Korea is also expanding.

Professor Kim explained that according to their own monitoring, adult lovebugs have been found this year in Dongducheon, Pocheon, and Gwangju in Gyeonggi Province, as well as in Cheonan, South Chungcheong Province.

The research team has recorded 648 cases of lovebug sightings nationwide this year.

However, they also analyzed that there may be a natural regulation of density as competition for habitats among the population has intensified following last year's mass outbreak.

"There is a limit to the number of insects that can inhabit a certain area, and I believe that limit was already exceeded last year, so it will be difficult for them to increase rapidly beyond that level in the future," Professor Kim said.

He also noted that spraying water, a method recommended by some local governments for lovebug control, is not very effective.

"Lovebugs have hairs on their wings that provide a waterproof effect, so they do not die when it rains, and they hide under leaves during heavy downpours," Professor Kim said. "Unless it is high-pressure water spraying, they will not die just from being sprayed with water."

He added, "It is better not to use insecticides because they can kill non-target organisms and lead to resistance. Instead, you can catch them using physical methods or electric fly swatters."
※ Please note: This article was translated by AI and may contain errors.