When does the Blue Winged Olive hatch?

May–October, typically 16:00–19:00. It starts from about 10°C, peaks around 14°C and tails off by 20°C.

How big is the Blue Winged Olive?

Spinner stage: 6–9mm. That matches a #14 hook.

Mayfly · Aquatic insect

Blue Winged Olive

Q: What flies imitate the Blue Winged Olive?

Blue Winged Olive, BWO Emerger, Sherry Spinner, CDC BWO, Greenwell's Spider, F Fly, Blue-Winged Olive Parachute, typically on a #14 hook.

Serratella ignita

Size

6–9mm

Hook size

#14

Hatch window

Season May–OctoberPeak time 16:00–19:00

Water temperature

14° peak

10°20°

How fish feed on it

The sherry spinner — named for the colour, which is exactly right in low evening light. This is the other half of the BWO problem: the fall overlaps the hatch, so the fish get a choice and take it. A spent pattern fished flush, without floatant, solves more refusals at dusk than another change of dun ever will.

Flies that imitate this