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Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

Mayfly Species Ephemerella needhami (Little Dark Hendrickson)

This small and slightly noteworthy mayfly appears during the finest hours of the year. Ernest Schwiebert describes an Ephemerella needhami day in Matching the Hatch:

"It was a wonderul morning, with a sky of indescribable blue and big, clean-looking cumulus clouds, and the water was sparkling and alive. You have seen the water with that lively look; you have also seen it dead and uninviting in a way that dampens the enthusiasm the moment you wade out into the current."

I have not fished a needhami emergence, but the exquisite nymphs show up often (though never abundantly) in my samples.

Where & when

Time of year : May-July

There are reports of this species producing fishable hatches in Pennsylvania, New York, Connecticut, Michigan, and Wisconsin.

Most authors say this hatch begins and peaks in late June and dwindles through most of July. However, in Mayflies: An Angler's Study of Trout Water Ephemeroptera , Knopp & Cormier list a different emergence date than other authors, stating that the hatch can begin in late May. I suspect this refers to the warmer climate of southern Pennsylvania, while others gave dates for the Catskills and Michigan.

Hatching behavior

Time of day : Late Morning

Knopp & Cormier report that the male and female duns are different colors and vary from stream to stream. Ernest Schwiebert in Nymphs Volume I: The Mayflies: The Major Species reports that they take off from the water quickly after emerging, meaning nymph and emerger patterns might be more appropriate than dun imitations.

Spinner behavior

Time of day: Evening

Habitat: Riffles and runs

Nymph biology

Current speed: Medium to Fast

Substrate: Usually vegetation, occasionally elsewhere.

This species has an unusually strong affinity for aquatic vegetation. Many authors have noted this and it is consistent with my samples as well.

Specimens of the Mayfly Species Ephemerella needhami

1 Male Dun
Male Ephemerella needhami (Little Dark Hendrickson) Mayfly Dun
See the comments for an interesting discussion of the identification of this dun.
8 Nymphs

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