AB Fish Report
Insect Encyclopedia

Blue-winged Olive

Baetis spp.

Baetidae

MayflyHook #18-225-7 mm body

Peak activity

JanFebMarAprMayJunJulAugSepOctNovDec
Blue-winged Olive — Nymph

Nymph

Small olive-brown nymph with three tails; swims actively when dislodged. B. tricaudatus is the most common Alberta species.

Blue-winged Olive — Adult

Adult

Olive body, gray-blue upright wings; classic small mayfly silhouette.

Habitat & hatch

Found in rivers, tailwaters, and spring creeks, most commonly in riffles and runs. Bottom-dwelling nymph; emerger mid-column; adult on surface film. Often associated with gravel and cobble. Emerges in riffles and runs; best surface activity on overcast afternoons. Spring and fall broods.

Timing

Individual emergence windows typically last 3 to 14 days. Strongest surface activity occurs around midday, and the afternoon.

Sources

  • Boerger & Clifford 1975 — Bigoray River
  • Harper 2006 — Baetis emergence cues