I have an ultraviolet bug zapper that I am wanting to lend to a friend that has horses. It is my hopes it will reduce the fly population.

Are flies attracted to ultraviolet light?
What other insects (besides moths) will be attracted to the light?

NC

In general many insects are attracted to light (phototaxis or phototropism), some more to the yellow end of the spectrum and some more to the blue-violet-uv end. Googling around, I found several sources claiming that various flies are attracted to uv, including fruit flies, houseflies, horse flies, and stable flies. I didn't find any truly authoritative articles, however, and the makers of bug zappers seem to hype their products as attracting all manner of flying pests.

A notable exception is mosquitoes, for which chemical attractants must be used.

I wish I could give a better answer. It would be best to hear from horse people with firsthand experience.