A standard fly mask is not generally used while riding, as the stiff mesh interferes with the bridle and the minimal visual impairment of the mesh still presents a safety issue. Other styles of insect protection gear are designed for use with a bridle.
It is uncommon to use a standard fly mask while riding due to its stiff mesh interfering with the bridle, which also causes minimal visual impairment that remains a safety issue. Different styles of insect-protection gear are specifically designed for compatibility with a bridle.