The One Million Roaches Powering Japan's Pest Control Giant

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Earth Corporation, a hygiene product manufacturer, gained attention for its response to the mass chironomid outbreak at the Osaka Kansai Expo site in Konohana Ward, Osaka City.

Known as a professional insecticidal and pest control company, Earth Corporation has introduced popular products like the household insecticide "Earth" and "Gokiburi (cockroach) HoiHoi." The company's strength lies in its distinctive approach to dealing with insects.

Remembering Its Roots

Although Earth Corporation is now headquartered in Tokyo, the company was founded in Namba, Osaka, in 1892. It later established a presence in Ako, Hyogo Prefecture, setting up a company there in 1925 and building a factory in 1943.

Even today, Earth Corporation maintains strong ties to the Kansai region, with its two plants in Ako accounting for 40% of the company's employees and 90% of its domestic production.

*"Gokiburi Hoi Hoi" is a popular cockroach trap made by Earth Corporation. (©Earth Corporation)*

Earth Corporation has also signed a comprehensive cooperation agreement with the Osaka Prefectural Government. In late May, at the prefecture's request, the company conducted an on-site survey at the Osaka Kansai Expo in response to the chironomid outbreak. Officials from the 2025 Japan International Exposition Association joined the survey.

Along with providing technical advice, the company supplied insect repellent sprays, insect repellent fans, and other related items.

Although the number of chironomids has declined since May, further outbreaks are expected. The company has stated that it "remains willing to cooperate with the association as needed."

Breeding for Science

Earth Corporation's ability to promptly tackle such requests stems from its proud asset — the company's "research institute."

Located at the Sakoshi Plant in Ako, one of the company's main production facilities, the research laboratory has more than 100 staff members, including researchers. One of them, Ritsu Ariyoshi, is a biological breeding expert.

"We keep more than 100 species of insects here," Ariyoshi explained. "That includes around 50,000 flies and mosquitoes each, and roughly one million cockroaches."

*A mosquito rearing case, with each box containing approximately 1,000 mosquitoes.*

Ariyoshi has been involved in breeding and research for nearly 30 years. He quickly separates countless mosquitoes into males and females, a distinction crucial for research, as only females suck blood. Once a week, he also enters the room where cockroaches are raised free-range to care for their food and water.

The large-scale breeding and raising of organisms supports research and development of new products such as insecticides and insect repellents. These organisms are studied to understand their ecology and characteristics, as well as to analyze their responses to the new chemicals being developed.

Honoring the Dead

Thanks to these ongoing efforts, the company can swiftly launch new products in response to emerging challenges. These include the invasion of designated alien species such as the redback spider and Argentine ants into Japan, as well as the spread of red bugs – a growing problem in South Korea and Europe since the fall of 2023.

The company hosts an annual "insect memorial service" to honor the insects that have sacrificed their lives to support its research and product development. For about 40 years, this event has been held every December at a temple in Ako City, marking the end of that year’s research and development efforts.

In December 2024, the remains of stink bugs, bed bugs, cockroaches, flies, and other insect species known for their rapid spread were carefully arranged in the main hall of a temple. Researchers attending the ceremony offered prayers for their repose in a solemn Buddhist ritual.

"We cannot advance product development without understanding the ecology of insects, and the insects we maintain in the laboratory are indispensable," said Research Director Tomihiro Kobori. "We join our hands in gratitude to them."

Culture in a Bottle

When I stopped by the Sakoshi factory cafeteria, a vending machine labeled "Katsugi-san's Treat Vending Machine" caught my eye.

"Katsugi refers to President Katsunori Kawabata," said Kobori. "If two employees tap their employee ID cards on the vending machine at the same time, they receive a free bottle, courtesy of the president’s treat."

The company believes that inviting anyone within the organization to join casual conversations can "provide valuable insights" and "spark great ideas." They encourage employees to connect and communicate with as many colleagues as possible.

These vending machines are installed at three locations, including the Tokyo headquarters and the Ako plant. It's this kind of in-house culture that helps spark the creation of hit products.