We have also been using the dryer sheets and they work great on the black flys.
We have found the Bounce Spring Awakening to work far better than all others, with the Bounce Outdoor Fresh Scent as a back-up. Both are much less expensive than bug spray and work much better than everything else we have tried. We got this information several years ago while camping during Memorial Day Weekend in the White Mountains.
I wonder if Proctor and Gamble are aware of all the uses of these products they market.
R2B