At Boston University in Massachusetts, the Ig Nobel Prize for biology was awarded on September 18, 2025 to (from left in the front row) Kazato Oishi, associate professor of Kyoto University’s Graduate School of Agriculture, Tomoki Kojima, researcher at the National Agriculture and Food Research Organization, and Sei Sato of the Aichi prefectural livestock research center. Photo: Jiji Press
It is the 19th consecutive year that Japanese researchers have received an Ig Nobel Prize, a spoof of the Nobel Prize that honors humorous but creative research.
The award ceremony was held at Boston University in the eastern U.S. state of Massachusetts.
Tomoki Kojima of the National Agriculture and Food Research Organization and other researchers painted white stripes on black cows with water-based paint to compare the number of insects attracted to them versus ordinary black cows.
To ensure the insect-repellent effect was not due to the smell of paint, they also observed black cows painted with black stripes.
A cow painted with white stripes for the experiment, from a research paper by researcher Tomoki Kojima of the National Agriculture and Food Research Organization and others. Photo: Jiji Press
The results showed that the number of blood-sucking insects attracted to the cows with the white stripes was about half that for the cows with black stripes or no paint.
A research paper on the results was published in 2019.
The mechanism by which the striped pattern repels insects is not fully understood, according to the group.
The paper said that the economic impact of blood-sucking flies on the U.S. cattle industry is estimated at more than 2.2 billion dollars annually.
The group’s research may help address the issue of some insects that are resistant to insecticides.
A demonstration project to create striped patterns by bleaching cattle’s body hair has already been conducted in Yamagata Prefecture, northeastern Japan.
Kojima had previously received consultations from farmers breeding wagyu beef about measures against blood-sucking insects, which led him to explore the hypothesis that zebra patterns could have an insect-repellent effect.
At the award ceremony, group members Kazato Oishi, associate professor at Kyoto University’s Graduate School of Agriculture, and Sei Sato of the Aichi prefectural livestock research center interrupted Kojima’s speech humorously by bringing panels with pictures of flies drawn on them closer to him.
Kojima then took off his jacket and revealed a zebra-patterned shirt to counter the disturbance, drawing applause from the audience.
“I was very surprised and wondered if it was a prank,” Kojima said of the award.
“I’m honored and very happy.”
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