Mayfly crawler multi-use pattern here. I use light hare's ear dubbing, colored on top with a brown umber prismacolor marker to give it a two-tone effect. Barred centipede legs are great here to add movement and mimic a dislodged crawler in the current. Non-toxic lead wire sub used for weight in underbody crimped flat to keep the profile slim like the natural. Just set to dry..Make them want it.
Observe and create.
More flies on deck...