Uni-Thread by Uni 8/0 Fly-Tying Material is by far the most popular thread for midge patterns. The continuous polyester filaments are bonded together in a compound twist. As a result, midge bodies with even a single layer of thread remain true to color, with no bleed-through when wet. 200-yard spool. Size: 8. Color:Purple. Cancer and Reproductive Harm- www.P65Warnings.ca.gov.