What New Research Tells Us
Since that first study in 2019, there's been a growing body of work exploring why zebra stripes seem to deter horseflies. Many of the results are pretty compelling, but it's always worth asking: how solid is this evidence?
A 2023 study from the University of Bristol found that rugs with sharp, thin black-and-white stripes seemed to reduce horsefly landings more effectively than plain or low-contrast designs. However, the sample sizes were limited, so real-world results might differ.
Then, 2022 research in Kenya showed that flies approached zebra and impala pelts similarly but avoided landing on zebra stripes up close (within about 30 cm). This suggests the stripes don't stop flies from getting near, but rather mess with their landing precision. Again, lab conditions aren't always a perfect match for a field full of horses!
Another 2022 study indicated that the width of the stripes (within a natural range) didn't seem to significantly alter fly behaviour. This implies that the presence of stripes is what matters, not their exact size. Though, "no significant difference" can sometimes mean "not enough data to spot a small effect," so keep that in mind.
There's even a "Thermal False-Vessel Hypothesis" from 2022… wait what? This theory essentially proposes that sunlit barrels painted with thin black lines attracted flies who mistook them for warm blood vessels, only to then fail to feed. The idea is that this thermal misdirection might play a role. It's a creative theory, but let's be real, horses aren't barrels, and the thermal properties of real fur are a bit more complex.
Finally, while earlier theories suggested "visual aliasing" (where stripes confuse a fly's motion detection) was key, more recent studies point to colour contrast and patch size as the most likely cause of deterrence. That's not to say optical effects are totally out, but it seems there might be multiple mechanisms at play.
So, What's the Verdict?
Despite the flaws in many of these studies, it seems most of the research suggests there could be some truth to the idea of the zebra print fly rug. While we can't say for certain why it works, or if a rug can truly mimic the skin of a zebra, it certainly seems logical from an evolutionary perspective that 'the horses of Africa' would develop their own natural adaptation for reducing flies. Opting for a zebra print, or possibly any two-toned, high-contrast fly rug, could be a worthwhile 'experiment' to see if it reduces the impact of flies on your horse this season.
Want To Know More?
Read the full article, Veronica's original review on the 2019 study and more on the current research content in the attached blog…
