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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
Blue-winged Olives
Baetis

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.

Dorsal view of a Sweltsa (Chloroperlidae) (Sallfly) Stonefly Nymph from the Yakima River in Washington
This species was fairly abundant in a February sample of the upper Yakima.
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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Identification: Key to Species of Agnetina Adults, Couplet 2

Identification: Key to Species of Agnetina Adults, Couplet 2

Adapted from Stark et al (1986)
Option 1Option 2
Ventral margin of femora dark forming mesal yellow window
Anterior view of femur of Agnetina capitata.
Anterior view of femur of Agnetina capitata. Figure source: Stark et al (1986)
Ventral margin of femora light
Anterior view of femur of Agnetina flavescens.
Anterior view of femur of Agnetina flavescens. Figure source: Stark et al (1986)
Apical portion of male hemitergal process long and sinuate, toe bluntly rounded
Lateral view of hemitergal process of male Agnetina capitata.
Lateral view of hemitergal process of male Agnetina capitata. Figure source: Stark et al (1986)
Swollen area of male hemitergal process adjacent to foot obscuring ankle area
Lateral view of hemitergal process of male Agnetina flavescens.
Lateral view of hemitergal process of male Agnetina flavescens. Figure source: Stark et al (1986)
Dark pirgment areas on female sterna 8 and 9 large quadrangular
Sterna 8 and 9 of female Agnetina capitata.
Sterna 8 and 9 of female Agnetina capitata. Figure source: Stark et al (1986)
Dark pigment areas of female sterna 8 and 9 not quadrangular
Sterna 8 and 9 of female Agnetina flavescens.
Sterna 8 and 9 of female Agnetina flavescens. Figure source: Stark et al (1986)
2 Example Specimens
Agnetina capitata Agnetina flavescens
Adapted from Stark et al (1986)
The current couplet is highlighted with darker colors and a icon, and couplets leading to this point have a icon.
Leads to Agnetina annulipes:
  • Femora transversely banded
  • Male hemitergal process foot-shaped with long slender ankle and toe
  • Female subgenital plate truncate, dark pigment covers sternum 8 in continuous mesal band
Leads to Couplet 2:
  • Femora longitudinally banded
  • Male hemitergal process either with toe blunt or ankle short
  • Female subgenital plate rounded with areas of basolateral dark pigment
Couplet 2
Couplet 2

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Couplet 2 (You are here)
Leads to Agnetina capitata:
  • Ventral margin of femora dark forming mesal yellow window
  • Apical portion of male hemitergal process long and sinuate, toe bluntly rounded
  • Dark pirgment areas on female sterna 8 and 9 large quadrangular
Leads to Agnetina flavescens:
  • Ventral margin of femora light
  • Swollen area of male hemitergal process adjacent to foot obscuring ankle area
  • Dark pigment areas of female sterna 8 and 9 not quadrangular

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References

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