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Salmonflies
Pteronarcys californica

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

Mayfly Species Acentrella turbida (Tiny Blue-Winged Olive)

Although these mayflies are tiny, in places their numbers compensate for their small size and make for excellent hatches.

Rick Hafele and Dave Hughes in Western Mayfly Hatches rate turbida as one of the three most "key" western species of Baetidae, alongside Baetis tricaudatus and Diphetor hageni. In the West, turbida is more variable in size and appearance than its eastern iteration, in keeping with the large and varied regions it inhabits. It can run as small as 3.5 mm and as large as 5 mm, the larger sizes tending to be more brownish. It is often confused with the smaller broods of Diphetor hageni, but its conical mesonotal projection, lack of hind-wings, exaggerated turbinate eyes (hence its name) and stockier build help to differentiate it.

They are often found on the water with a mix of other Baetidae mayflies, making for very challenging fishing.

Taxonomic History

Acentrella turbida was previously known as Pseudocloeon carolina in the East and Pseudocloeon turbidum in the West. Combining these putative species made this one of the most widely distributed mayflies in North America.

Where & when

Time of year : May through October

In Hatches II, Cauci and Nastasi report excellent hatches of this species on Pennsylvania spring creeks, with broods in May, August, and October. They are probably important on similar waters across the country.

Ted Fauceglia's Mayflies mentions Eastern broods of Acentrella hatching from late June to early July and again in September and October, plus a possible earlier brood in late May. Schwiebert mentions in "Nymphs" they can provide excellent fishing in the Fall out West.

Seasonal emergence timing varies from water to water, and these flies may possibly be found at any time of the season depending on locale.

Spinner behavior

The large turbinate (raised on stalks) eyes of the male imagos are the reason for this species' name. They are capable of molting quickly, and morning dun hatches often provide excellent spinner fishing that evening.

Nymph biology

The nymphs are stouter in proportion compared to other baetids, but their behavior is similar.

Specimens of the Mayfly Species Acentrella turbida

3 Female Spinners
1 Male Spinner
Male Acentrella turbida (Tiny Blue-Winged Olive) Mayfly Spinner
I would not like to have to match this hatch. These are the smallest mayflies I have ever seen. I used to think Caenis was the smallest adult mayfly in the west but these guys are about 4mm long. The male eyes are two toned, brown above and olive below. The abdomen is dark brown interspersed with light brown. The abdomen is clear for the anterior 2/3rd and the remainder is white. The tails are twice as long as the insect. There is only one pair of wings.

2 Streamside Pictures of Acentrella turbida Mayflies:

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References

Species Range
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