The sudden proliferation of bed bugs in cities such as Daegu and Incheon has now reached Seoul, a capital with a population of 9.7 million people, and this is leading to a surge in demand for insect repellents.

According to Dongsung Pharmaceutical, sales of their repellent Biokill in October have skyrocketed, recording a 10-fold increase compared to the same period last year.

Recently, bed bugs have spread panic not just in major European cities like Paris but also throughout Korea. These pests, which feed on human blood, can cause skin inflammations like red blisters and hives.

According to the government, the onset of colder weather and subsequent increase in indoor heating, creating warmer environments, has exacerbated the issue.

There have already been reports of bed bugs in numerous saunas and university dormitories across the nation, with over half of Seoul's 25 districts now engaging in extermination efforts.

Biokill, a colorless and odorless insecticide developed by the Swiss company Jesmond, is environmentally friendly and has a low toxicity profile.

According to Dongsung, its unique mechanism incapacitates the nervous system of pests, ensuring sustained efficacy for about four weeks after a single spray.

Also, given that it's 99 percent water-based, users can apply it to bedding, clothes, fabric sofas, and rugs, without worrying about stains or damage.

Though effective against a range of pests like cockroaches, flies, mosquitos, fleas, and ticks, Biokill is especially known for its potency against bed bugs.

This heightened demand for Biokill has positively impacted DongSung's stock prices, with shares surging by 16 percent since Korea reported its first bed bug citing in Incheon on Oct. 16, closing at 6,480 won ($4.77) on Wednesday.

"Given the growing fear of bed bugs even in Seoul, many are purchasing BioKill as a precautionary measure," a Dongsung official said. "Consumers can rest assured about the product's safety as it has received approval from the U.S. Environmental Protection Agency (EPA)."

Dongsung isn't the only beneficiary of the bed bug scare.

Kyung Nam Pharma, another player in the insect repellent market, has seen its stock prices surge.

Kyung Nam's bug-repellent product contains Icaridin, a compound proven to be effective against blood-sucking insects.

Registered with the EPA as an insect-repellent ingredient since 2001, Icaridin's safety has also been endorsed by the Ministry of Food and Drug Safety.

Thanks to the increased demand, the company's shares hit their upper limit on Tuesday, closing at 1,519 won, a 29.9 percent increase from the previous trading day, and continued to soar, ending at 1,670 won on Wednesday, up 10.01 percent.

Meanwhile, the government met with related ministries on Tuesday to discuss management and extermination measures for bed bugs in shared accommodation facilities.