🐂 Painting Cows Like Zebras: The Ig Nobel Prize-Winning Study 🦓

Before you scroll, take a guess why is this cow painted like a zebra?

Alright, here’s the answer.

In a creative approach to pest control, a group of Japanese researchers found that painting cows with zebra-like stripes can significantly reduce the number of biting flies that land on them. This unusual yet effective idea earned the team the 2025 Ig Nobel Prize in Biology, an award that celebrates research that is both amusing and thought-provoking.

 The Study

Led by Tomoki Kojima of the Aichi Agricultural Research Center, the researchers set out to test whether zebra-style stripes could protect livestock from biting insects without using chemical repellents. The experiment involved Japanese Black (Wagyu) cows, which have naturally dark coats.

 The cows were divided into three groups:

a) White-striped cows, painted with zebra-like patterns.

b) Black-striped cows, painted with black lines that blended into their coats.

c) Unpainted cows, which served as the control group.

The team observed the cows in a pasture, counting how many flies landed on each and recording behaviors such as tail flicking, head shaking, and skin twitching, which indicate irritation from insect bites. (please refer to the image below)

The Results

The results were striking. Cows painted with white zebra-like stripes attracted about half as many biting flies as unpainted or black-striped cows. They also showed fewer defensive movements, suggesting they were less bothered by insects.

The researchers concluded that the pattern of contrasting stripes, rather than the paint itself, was responsible for the effect. One possible explanation is that the stripes confuse the flies’ visual system or disrupt the way they perceive polarized light, making it harder for them to land accurately.

Why It Matters

Biting flies do more than annoy livestock. They cause stress, reduce feeding and milk production, and can transmit diseases. Traditional insect repellents and pesticides are costly and can have environmental or health impacts. Painting cows with water-based paint offers a low-cost and chemical-free alternative that could help farmers reduce insect harassment.

The findings also support a long-standing idea in evolutionary biology: zebra stripes may have evolved to repel biting flies. By copying this natural design, scientists have created a simple and practical solution inspired by nature.

The Ig Nobel Prize celebrates discoveries that make people laugh and then make them think. What started as a playful idea has turned into a promising step toward sustainable pest control in agriculture.

Citation:

Kojima, T., Oishi, K., Matsubara, Y., Uchiyama, Y., Fukushima, Y., Aoki, N., Sato, S., Masuda, T., Ueda, J., Hirooka, H., & Kino, K. (2019). Cows painted with zebra-like striping can avoid biting fly attack. PLOS ONE, 14(10), e0223447. https://doi.org/10.1371/journal.pone.0223447

https://www.the-scientist.com/zebra-cows-repel-flies-and...

https://www.bbc.com/news/articles/crkjzxrrkd5o

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