Findings reveal that stark black-white distinctions and small dark patches are particularly effective in thwarting horsefly attack. These characteristics specifically eliminate the outline of large monochrome dark patches that are attractive to horseflies at close distances. 

The team theorise that the thin back stripes serve to minimise the size of local features on a zebra that are appealing to the biting flies. 

The research was led by Professor Tim Caro and Dr Martin How both from the University of Bristol’s School of Biological Sciences. 

Read the full University of Bristol news item

Paper: ‘Why don’t horseflies land on zebras’ by Tim Caro, Martin How et al. in Journal of Experimental Biology.