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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 Amphizoa (Amphizoidae) Beetle Larva from Sears Creek in Washington
This is the first of it's family I've seen, collected from a tiny, fishless stream in the Cascades. The three species of this genus all live in the Northwest and are predators that primarily eat stonefly nymphs Merritt R.W., Cummins, K.W., and Berg, M.B. (2019).
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

Identification: Key to Species of Agnetina Adults

Adapted from Stark et al (1986)
Option 1Option 2
Femora transversely banded
Anterior view of femur of Agnetina annulipes.
Anterior view of femur of Agnetina annulipes. Figure source: Stark et al (1986)
Femora longitudinally banded
Dorsal view of middle and hind femora of an Agnetina capitata male.
Dorsal view of middle and hind femora of an Agnetina capitata male. Figure from this Male Agnetina capitata adult.
Anterior view of femur of Agnetina capitata.
Anterior view of femur of Agnetina capitata. Figure source: Stark et al (1986)
Anterior view of femur of Agnetina flavescens.
Anterior view of femur of Agnetina flavescens. Figure source: Stark et al (1986)
Male hemitergal process foot-shaped with long slender ankle and toe
Lateral view of hemitergal process of male Agnetina annulipes.
Lateral view of hemitergal process of male Agnetina annulipes. Figure source: Stark et al (1986)
Male hemitergal process either with toe blunt or ankle short
Lateral view of hemitergal process of male Agnetina capitata.
Lateral view of hemitergal process of male Agnetina capitata. Figure source: Stark et al (1986)
Lateral view of hemitergal process of male Agnetina flavescens.
Lateral view of hemitergal process of male Agnetina flavescens. Figure source: Stark et al (1986)
Female subgenital plate truncate, dark pigment covers sternum 8 in continuous mesal band
Sterna 8 and 9 of female Agnetina annulipes.
Sterna 8 and 9 of female Agnetina annulipes. Figure source: Stark et al (1986)
Female subgenital plate rounded with areas of basolateral dark pigment
Sterna 8 and 9 of female Agnetina capitata.
Sterna 8 and 9 of female Agnetina capitata. Figure source: Stark et al (1986)
Sterna 8 and 9 of female Agnetina flavescens.
Sterna 8 and 9 of female Agnetina flavescens. Figure source: Stark et al (1986)
Remaining species: Agnetina capitata and Agnetina flavescens
2 Example Specimens
Agnetina annulipes Go to Couplet 2
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.
Couplet 1

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Couplet 1 (You are here)
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
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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