Epeorus longimanus and Epeorus albertae are the two most common Epeorus species in the West. Where & When
» Species longimanus (Slate Brown Dun)
Region:According to Ernest Schweibert in Matching the Hatch, the trout "respond very well" to this hatch. Fred Arbona in Mayflies, the Angler, and the Trout called the hatches disappointing, noting that they may be overshadowed by simultanenous hatches of Rhithrogena hageni.Hatching Behavior
WestTime Of Year (?):
June through mid-August, peaking in mid-June to mid-July, for about one week in any given locationAltitude:
Above 5,000 feet
Time Of Day (?):The nymphs emerge sporadically on the bottom in the shallows and rise to the surface as duns.Spinner BehaviorTime Of Day: Midday
Anytime; sometimes concentrated in late morning
Habitat: Fast water
Current Speed: FastThis species is found more in the cold headwaters than Epeorus albertae and Epeorus grandis.
Pictures of 3 Mayfly Specimens in the Species Epeorus longimanus:
Female Epeorus longimanus (Slate Brown Dun) Mayfly Spinner
View 1 PicturesI associated this female with a male I collected one night later. For a great and informative discussion of all Epeorus species and other mayflies be sure and read, WESTERN MAYFLY HATCHES by R. Hafele and D. Hughes. They rate all of the western mayflies and they rate the hatch of this genus a 25 out of a possible 45 points based on several rating criterion. They provide insect photos, possible fly patterns and fly presentations. This is a great book.
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