I tested your theory of powder the other day and it made no difference. Perhaps it was the color of your shirt that day, or the amount of CO2 your body was producing that day. Maybe it was at the hight of their hatching that week, or maybe bugs find you cute...
I tried the different powders just to see if there was a difference. The black flies, sand flies and skeeters did not seem to care what flavor powder was out there, only me... It was a case where I was not happy being noticed....