Black Fly

LARVA SIZE: 3-7 mm (1/8 to 1/4 in)

LARVA COLOR: Smoky gray, dirty yellow, creamish, or black

PUPA SIZE: 3-7 mm (1/8 to 1/4 in)

PUPA COLOR: Silvery case over black adult

ADULT SIZE: 3-7 mm (1/8 to 1/4 in)

ADULT COLOR: Black

OTHER CHARACTERISTICS: Back third of larva is much thicker than front

About Black Flies

Black flies are the most important trout food that nobody imitates. Note: this doesn't say black flies are the most important trout food. Just the most important one that nobody bothers to tie flies for.

Black fly larvae are abundant in many running water habitats. They hold on tightly to rocky substrates. Pupation occurs underwater, and the fully-formed adult rises to the surface encased in a silvery bubble of gas. That bubble keeps their wings dry, so black fly adults emerge at the surface and instantly fly away. For this reason, you never see any rise forms duringn a hatch.

The best fly fishing tactic is to dead-drift a larva pattern through quick flowing, rocky habitat deep enough to hold trout; use tight line nymphing tactics to present a rising adult. You can also cast adult patterns where riffle water starts to slow at the head of a shallow run, but nymphing with a larva pattern is more productive.

There is an excellent two-part article on black flies and their imitations in the Westfly archives.

Articles About Black Flies

Click headline to read entire article

Black Flies: Part One If Bob Dylan were a fly angler, he'd have sung about black flies. And after you learn about this depised, neglected, and rejected insect, you'll be singing too. Jeff Morgan

Black Flies: Part Two-The Patterns Ignored by anglers, gobbled by trout. Would Dylan approve? Jeff Morgan

STAGE

PATTERN

SIZE/
COLOR

PRESENTATION

WHERE

Whitefish

Egg Fly

6-10/Pink, peach, white, purple, many others

Indicator, Tight line

Rivers