best black fly killer?

["Michelle Rowe" <michrowe@frontier.net>]

black flies are coming out.  anyone know something that REALLY kills em?

 

we're using:

 

big stinky flytraps

fly paper

diatomaceous earth

fly mask on horse

 

any other remedies would be great.  they're making me and my horse crazy.

 

thanks -

 

m