This is a nicely tied pattern by Arrick’s Fly Shop out of West Yellowstone, Montana.
Ants are hard to see, so tying them as a parachute pattern makes them easy to see. I tie this pattern in black, cinnamon/black, and cinnamon. The cinnamon color is especially effective when the honey colored flying ants are landing on the water. We see these starting in mid August. The cutthroats in the northeast corner of Yellowstone park like this fly.