I enjoyed a pleasant time on the day of the Fun Fly.  However there were some deer fly visitors that seemed to be annoying.  Today I was visiting another field and the deer fly population was plain and simply vicious.  On my return I did some on-line research.  It turns out that blue is the color most attractive to deer flies.  There are other interesting ways to combat them.  At the field, deer fly traps would put a big dent in the population.  They are pretty cheap to make.

Below are several links and some back story.
The 2nd and 3rd could be applied at the field.

http://www.rci.rutgers.edu/~insects/greenheads.htm
http://deerflytrapumbrella.blogspot.ca/
http://www.instructables.com/id/Deer-Fly-Traps/?ALLSTEPS
http://www.leevalley.com/en/garden/page.aspx?p=10293&cat=2,51555,10293

Russ Mizell, an entomologist with the University of Florida's Institute of Food and Agricultural Sciences, counts the number of deer flies captured on a simple control device he invented (Monday--August 12, 2002). After numerous experiments aimed at controlling the pesky insects, Mizell said the trap that attracted the most deer flies is a 6-inch flower pot painted bright blue and covered with a sticky spray. The trap, which captured as many as 30 deer flies in a one-minute test, is most effective when it's suspended three to six feet above ground and "trolled" or moved no faster than 10 feet per second. (University of Florida photo by Tara Piasio)

Continued next post

A flying friend cheekily suggested that to avoid being bitten by deer flies on Sunday, he went to church.  He said he was not bitten, or pestered, by a single deer fly while at church.

YMMV

a 20 ga. shot gun, loaded with blue "dust" shot is also effective.."buck" shot is no good, it's only effective against the deer itself.   

Bizarre, but worth a try. Now if we only still had shiny new pennies.