Japanese team wins 2025 Ig Nobel prize for Zebra-striped cow experiment

A Japanese research team earned the 2025 Ig Nobel Prize in the biology category on September 18 for an unusual experiment: disguising a cow as a zebra to repel bloodthirsty insects.

This marks the 19th consecutive year that a team from Japan has claimed an Ig Nobel, a parody of the Nobel Prize that celebrates research both thought-provoking and humorous. The award is organised by the Annals of Improbable Research magazine, which focuses on quirky scientific topics, the Asahi Shimbun writes. 

“We’re deeply honored to receive this award. I still can’t believe that we really won,” said Tomoki Kojima. Now a fixed-term researcher at the National Agriculture and Food Research Organization, Kojima led the study while working for a department supporting livestock farmers at the Aichi Agricultural Research Center.

The idea for the study arose after Kojima learned about the problems livestock farmers face due to blood-sucking insects such as horseflies and stable flies. These pests can spread diseases like bovine leukosis and cause stress through bites, which may stunt growth and reduce milk production.

Three black cows were chosen as the subjects of the experiment after Kojima encountered a theory suggesting that zebras’ patterns deter hungry insects. One cow was painted with white stripes to mimic a zebra, another was given black stripes, and a third was left unpainted.

Researchers monitored the cows by analyzing photographs and counting the number of blood-sucking insects visible from the right side. They found that the white-striped cow had half as many insects as the other two and displayed fewer insect-repelling behaviors such as head shaking and tail swishing.

The findings suggest that painting cows and other livestock with zebra-like stripes could offer an environmentally friendly alternative to insecticides, benefiting both human and animal health.

“To spread use of this method, it is necessary to develop new, easy ways to paint livestock with zebra stripes that last a long time,” Kojima said.

By Sabina Mammadli