In some areas where a control agent was sprayed before lovebugs (Plecia nearctica) emerged as adults, up to 98% fewer adults were trapped than in nearby unsprayed areas. However, because the control effect was unclear in some locations, the government plans to continue inspections through July and then decide whether to conduct additional spraying.
◇At Bukhansan Bulamsan spray sites, 98% fewer lovebugs than in unsprayed areas
According to materials received on the 27th by Rep. Kim Wi-sang of the People Power Party from the Ministry of Climate, Energy and Environment (the ministry), traps in unsprayed points within Bulamsan in Nowon District, Seoul, captured 249 adult lovebugs over two days starting on the 16th. During the same period, traps at sprayed points within Bulamsan captured only four adults. The number where the control agent was applied was 98.4% lower than in unsprayed areas.
A similar result came from Sahmyook University in Nowon District. In unsprayed areas, 233 adult lovebugs were captured, while only four were trapped at sprayed sites, a 98.3% reduction. In Suraksan in Nowon District as well, unsprayed areas saw 244 captured versus 22 in sprayed areas, a 91% difference.
In addition, ▲Dodeoksan in Gwangmyeong, Gyeonggi (100%) ▲Baengnyeonsan in Eunpyeong District, Seoul (84.4%) ▲Onansan in Siheung, Gyeonggi (71%) ▲Bongsan in Eunpyeong District (69%) ▲Gwanaksan in Anyang (50%) also had fewer adult lovebugs in sprayed areas than in unsprayed areas.
◇18 locations in the capital area sprayed with lovebug control agent since April
Earlier, the ministry took preemptive control measures to reduce lovebug numbers. In 18 capital-area locations identified as lovebug occurrence sites—five in Seoul, four in Incheon, and nine in Gyeonggi—control agents were sprayed twice starting in April. The timing took into account that lovebug larvae typically pupate around mid-May and emerge as adults from June.
The operation used a Bacillus thuringiensis israelensis (BTI) soil-bacteria control agent developed under the lead of Kim Dong-geon, head of the Environmental Ecology Research Institute at Sahmyook University. BTI acts on the guts of specific insects to kill larvae, and it is known to have relatively limited impact on plants and surrounding ecosystems.
But not all areas showed the same results. There were cases where more lovebugs were caught in sprayed areas. On Jeongbalsan in Goyang, Gyeonggi, 67 were captured in sprayed areas, compared with 12 in unsprayed areas. ▲Cheonmasan in Gyeyang and Seo districts of Incheon ▲Gahaksan in Gwangmyeong ▲Seodoksan in Gwangmyeong ▲Seongjusan in Bucheon also recorded more captures in sprayed areas than in unsprayed areas.
Kim, who led the control efforts, said, "Some areas began work from mid-May, the timing of the second round, which is when larvae transition to pupae," and added, "The results may depend on timing."
◇Regional variation exists… "Need to factor in climate effects"
Beyond whether spraying occurred, weather conditions and movement routes may also have affected numbers. With the monsoon delayed and regional temperatures and wind flows shifting, the timing and density of lovebug occurrences may have changed. On the 24th, when the National Institute of Forest Science expected lovebug activity to peak this year, fewer lovebugs than anticipated were reported near Gyeyangsan in Incheon. By contrast, in northern Gyeonggi, including Dongducheon and Uijeongbu, large outbreaks occurred earlier, from March to April.
Areas filing lovebug-related complaints are also changing year by year. In 2022, 3,558 cases—80.5% of all lovebug complaints in Seoul—were concentrated in Eunpyeong District. The following year, they spread to Seoul's northwestern area and to Goyang, Gyeonggi, and since then related complaints have continued across the entire capital region.
Yang Yeong-cheol, a professor in the Department of Public Health, Environment and Safety at Eulji University, said, "Lovebugs have weak flight capability and move with wind direction and flow," and noted, "It is premature to conclude there is a reduction effect from preemptive control."
◇Kim Wi-sang: "Lovebugs require a nationwide quarantine network"
The government plans to review the results of the control efforts through late July and then, centered on the "Insect Outbreak Response Council" involving local governments and experts, discuss additional measures.
A ministry official said, "We will compare changes in flies, other insects, and arthropods inhabiting the surrounding soil before and after spraying to decide on additional adoption of control agents."
Rep. Kim Wi-sang said, "A bill designating lovebugs as 'outbreak insects' and imposing control obligations on local governments passed the National Assembly's plenary session last month," and urged "the operation of a systematic nationwide quarantine network."