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Hatches › Mayfly
Callibaetis · genus
Speckled Duns are small mayflies whose nymphs and soft-water hatches can bring steady surface feeding.
Category
Mayfly
Category
The insect or forage category for this profile.
Size
Generally small, most often imitated in sizes 14–18.
Size
Typical size range anglers imitate on the water.
Key stages
Eggs, Nymph, Emerger, Adult / Dun, Spinner, Egg Laying Spinner, Spent Spinner
Key stages
Life stages most relevant to fly fishing this hatch or forage.
Water types
lakes, ponds, sloughs, slow backwaters
Water types
Water types where this bug or forage is commonly found.
Callibaetis is a genus of mayflies in the family Baetidae, commonly called Speckled Duns. For Idaho anglers, they matter most as a stillwater and slow-water mayfly matched with nymphs, emergers, duns, and spinners.
Also known as: Speckled Dun
Female mayflies lay hundreds to thousands of eggs in or near the water. These eggs then sink to the stream bottom to develop.
Mayfly nymphs live on the stream bottom, feeding and growing through a series of molts. This stage typically represents the longest part of their life cycle.
When ready, the nymph rises to the water's surface, where it transforms into an adult. This is a critical stage for fly anglers as fish often key in on these vulnerable insects.
The freshly emerged adult, known as a dun, rests on or just above the water's surface. It waits for its wings to dry and harden before taking flight.
After molting one last time in the air, the dun becomes a sexually mature spinner. Mated adults then gather to reproduce, often in large swarms.
Following mating, the female spinner returns to the water's surface to deposit her eggs. This ensures the continuation of the mayfly life cycle.
After successfully laying her eggs, the adult mayfly, now a spent spinner, dies. These spent adults often float on the water's surface, providing an easy meal for hungry fish.
nymph
Fly Fish Food
Materials
emerger
RiverKeeper Flies
Materials
Adult / Dun
Phil Rowley Fly Fishing
Materials
Egg Laying Spinner
RiverKeeper Flies
Materials
Spent Spinner
Phil Fischer
Materials
Callibaetis
One species, multiple rivers.
