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Artistic view of a Male Pteronarcys californica (Pteronarcyidae) (Giant Salmonfly) Stonefly Adult from the Gallatin River in Montana
Pteronarcys californica

The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.

27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
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Mayfly Genus Callibaetis (Speckled Duns)

The speckle winged Callibaetis genus contains on average the largest species in the Baetidae family with hatches ranging in size from 20 to 12 (6mm to 12mm). However, most can be matched with 14 and 16 imitations. They reside only in very slow weedy sections of rivers or lakes and ponds.

The most important are the sub-species Callibaetis ferrugineus ferrugineus in the East and Midwest and Callibaetis ferrugineus hageni in the West. It is in the West however, where this genus achieves its densest populations and most significant hatches. Other important western species also happen to be at both sides of the size scale. The outsized Callibaetis californicus can produce excellent hatches. The diminutive Callibaetis pictus can also be locally prolific, especially at higher elevations.

The duns are easily recognized by their speckled bodies and distinctive wings usually featuring a dark background overlaid with white veins. Female spinners are also easy to recognize with their clear wing's leading edges marked with dark blotches -- see the pictures.

Where & when

Time of year : May through October; best in Summer

Preferred waters: Mostly lakes and ponds; sometimes slow rivers

Callibaetis species usually produce two and sometimes up to three broods in a single season. Their peak times vary widely by location.

In 209 records from GBIF, adults of this genus have mostly been collected during July (19%), June (19%), August (18%), May (14%), April (10%), and September (8%).

In 173 records from GBIF, this genus has been collected at elevations ranging from 20 to 12402 ft, with an average (median) of 4288 ft.

Genus Range

Hatching behavior

Time of day : Daytime

Callibaetis duns emerge on the surface. They can take flight quickly or ride the water's surface for a lengthy period, depending on circumstances. Knopp and Cormier write in Mayflies: An Angler's Study of Trout Water Ephemeroptera that the nymphs make several trips to and from the surface before hatching, a habit more common in the Ephemerellidae family.

The hatch may last for several hours during the cooler weather of spring. In the West, duns most often appear mid-morning before the ever present wind comes up. Soft overcast days are optimal and during these conditions the duns will come off in waves lasting for hours. Mixed with nymphal activity and interpersed with spinner falls, the trout are presented with quite a feast.

Spinner behavior

Time of day: Dusk

Fred Arbona describes the distinctive look of the airborne spinners in Mayflies, the Angler, and the Trout:

They have distinctive flight patterns consisting of foot-long, fast vertical undulations as if they were suspended on invisible rubber bands.

Angling literature is replete with descriptions of this behavior often referred to romantically as the "mating dance."

A very interesting quirk of this genus is evidence that suggests the tiny nymphs hatch from fertilized eggs almost as soon as they hit the water. To make this possible, the females would have to wait on land for an extended period after mating to allow incubation before they can oviposit.

They often spend considerable time on the water either during or immediately after ovipositing and they often do this in a full upright or semi-spent condition, at least at first. This offers excellent dry fly opportunities. The spinner falls can occur at any time during daylight hours so it pays to be observant and prepared. In the West, ovipositing seems to be more dependant on wind than any other factor. As with the duns, during periods of calm they can come on in waves only to dissipate quickly as wind comes back.

Knopp and Cormier offer a good tip for fishing the spinners:

The natural spinner's tails are widely spread, and this trait should be copied on all imitations.

Nymph biology

Current speed: Still or slow

Substrate: Vegetation, silt

The nymphs are excellent swimmers in their slow-water environment. They dart around through the aquatic vegetation, often perching on stems and leaves in plain view of their predators. Trout often forage actively through the weeds for them, stirring up the plants to knock the nymphs loose. As mentioned above, the nymph's habits prior to emergence further expose them to trout predation. Fishing nymphal imitations on a greased leader in and around weed beds with slow twiches and short strips is often a deadly technique, particularly during the prehatch period in calm conditions. Because these nymphs are so common in some waters, their imitations make good searching patterns when nothing's hatching.

Specimens of the Mayfly Genus Callibaetis

1 Male Dun
5 Female Duns
3 Male Spinners
5 Female Spinners
1 Nymph

1 Streamside Picture of Callibaetis Mayflies:

Discussions of Callibaetis

Mayfiles other than Callibaetis
1 replies
Posted by Royal_Coach on Jan 15, 2018
Last reply on Jan 15, 2018 by Millcreek
every book/article I read says Baetidae is the most imporant family and Callibaetis the most important genus of mayfly. Why? Does this just mean they are the most prolific? Am I not likely to encounter any other family/genus on a western river?
Callibaetis Spinner Habits
8 replies
Posted by WildcatRob on Sep 8, 2007 in the species Callibaetis ferrugineus
Last reply on Jan 7, 2009 by Dgracia
With almost 40 years lake fishing experience in the Northwest (Washington) our callibaetis always seem to start hatching mid afternoon in the evening, mate overnight then the spinners start in the morning. The spinners draw the most intense "rise." I put rise in quotes because it is so delicate there it leaves almost no disturbance at all not even a sip.

Any comments? Hopefully contradictions?


Start a Discussion of Callibaetis


Mayfly Genus Callibaetis (Speckled Duns)

Genus Range
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