Why do zebras have stripes?
Let me sum up the leading idea in 30 seconds.The leading idea is that stripes help keep away blood-sucking flies such as horseflies. Experiments have shown that flies can't slow down properly over stripes and often fail to land. However, the exact reason why flies have trouble landing is still not clearly understood.
A long-standing mystery
What zebra stripes are for has puzzled scientists for a long time. Many ideas have been suggested: to hide in tall grass, to confuse the eyes of predators, to control body temperature, or to help zebras recognize each other. But not many of these ideas are firmly supported by experiments and observations.
The leading "fly-repellent" idea
The idea backed by the most evidence today is that stripes help keep away blood-sucking flies such as horseflies and stable flies. In Africa, horseflies can carry diseases that are deadly to zebras. Zebras also have short, thin coats, so their bodies are easy for flies to bite.
Observations compared with horses
A British research team watched how horseflies behaved around zebras and horses kept on a farm. The flies circled both animals about the same number of times, but fewer of them managed to land on the zebras. Video showed that horseflies approaching zebras could not slow down properly and often bumped into them and flew off. Also, when the same horses wore striped coats, horseflies landed on them less than when they wore black or white coats.
Based on the same study described in the text, which observed zebras and horses on a farm in Britain (Caro et al.).
Stripes that work up close
In another experiment in Kenya, stable flies also preferred to land on plain brown hides rather than striped hides. Both studies suggest that stripes don't keep flies away from a distance, but get in the way of landing up close. Why flies fail to land, and how their eyes are involved, is still not known.
Want to know more?
- Zebras also often swish their tails or run away. They are thought to avoid fly bites with both their stripes and their behavior.
- On horses wearing striped coats, the number of horseflies landing on their uncovered heads did not change. The stripes protected only the parts they covered.
- Between the hides of plains zebras, which have wide stripes, and Grevy's zebras, which have narrow stripes, there was no difference in how often flies landed.
Quick quiz: test yourself
What is the leading idea for why zebras have stripes?
Show the answer
- To hide from predators
- To keep biting flies away
- To recognize each other
To keep biting flies away Experiments show that horseflies and other biting flies can't slow down well over stripes, so they often fail to land.
Experiments show that horseflies and other biting flies can't slow down well over stripes, so they often fail to land.
Next quiz ›Sources
- Benefits of zebra stripes: Behaviour of tabanid flies around zebras and horses (PLOS ONE, 2019)PLOS ONE（Caro ほか, カリフォルニア大学デービス校・ブリストル大学など）
- Zebras of all stripes repel biting flies at close range (Scientific Reports, 2022)Scientific Reports（Tombak ほか, プリンストン大学など）
This article was written after checking the sources above as of 2026-10-03. Explanations may change as research progresses. Photo credits are shown below each photo.
