These small, dense patterns are designed to sink very quickly, even in the fastest of flows. Features like tungsten beads and UV-cured bodies make them heavy, and a relative lack of any peripheral features (legs, heavy-dubbed thoraxes, etc.) that would impede the flies’ sink rate turn them into tiny anchors.

FLY RECIPE (PMD):

Hook:  TMC 413J, #16 & #18
Bead:  Slotted Tungsten – Gold; to match hook size
Thread:  Ultra 140 Thread – Orange
Tail:  Z-Lon (Polytron Yarn, McFlylon Poly Yarn, or Antron Yarn) – Brown; sparse
Abdomen:  Ultra 140 Thread – Orange; ribbed with pearl Flashabou and coated with Loon UV Flow
Thorax:  Dubbing – Bright Yellow; preferably with some flash to it.  Ice Dub – UV Hot Yellow will work
Legs:  Same as tail (Polytron Yarn, McFlylon Poly Yarn, or Antron Yarn)

CA Warning:  WARNING: Cancer and Reproductive Harm - https://www.P65Warnings.ca.gov/product