Fly rugs do they keep horses cooler?

[Vodkagirly]

Went XC schooling at a venue where I am competing next it week, flies and cleggs were out in force and really bothering him. Obviously I'll coat him in repellent but what else can I do to keep him cool and unbothered since he will be hanging around all day. Is it worth getting a fly rug to keep him covered between phases? We don't have many flys around are yard as it is at the coast so would it keep him cooler then.

 

[asmp]

I was looking after a friends horse this weekend. She was very hot under her fly rug (Rambo one) while my two, who don't wear them, were fine.