Black Gnat (from Favorite Flies and Their Histories -1892 - by Mary Orvis Marbury)

hook: #22 (or very small) dry
thread: black 14/0
tag: gold
body: black ostrich herl
wings: black (dark dun) or gray hackle tips

Head cement recipe:
Goop
Xylene (epoxy thinnner)

Instructions:
Fill a quart jar half full with Xylene
Squeeze a tube of Goop into the Xylene
Shake until the Goop is dissolved; add Xylene to desired consistency

Apply with a pin or needle dipped in the liquid

https://youtu.be/AJbvJUixaCs