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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

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 Ephemerella mucronata (Ephemerellidae) Mayfly Nymph from the Yakima River in Washington
This is an interesting one. Following the keys in Merritt R.W., Cummins, K.W., and Berg, M.B. (2019) and Jacobus et al. (2014), it keys clearly to Ephemerella. Jacobus et al provide a key to species, but some of the characteristics are tricky to interpret without illustrations. If I didn't make any mistakes, this one keys to Ephemerella mucronata, which has not previously been reported any closer to here than Montana and Alberta. The main character seems to fit well: "Abdominal terga with prominent, paired, subparallel, spiculate ridges." Several illustrations or descriptions of this holarctic species from the US and Europe seem to match, including the body length, tarsal claws and denticles, labial palp, and gill shapes. These sources include including Richard Allen's original description of this species in North America under the now-defunct name E. moffatae in Allen RK (1977) and the figures in this description of the species in Italy.
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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Mayfly Family Metretopodidae (Pseudo-Gray Drakes)

The mayflies of this family are large and elegant as adults and among the fastest-swimming of all mayfly species as nymphs. Sadly only one species (Siphloplecton basale) has been reported to produce fishable hatches, and even those are exceedingly rare.

Where & when

In 74 records from GBIF, adults of this family have mostly been collected during June (35%), July (20%), April (14%), August (12%), March (9%), and May (7%).

In 349 records from GBIF, this family has been collected at elevations ranging from -30 to 3524 ft, with an average (median) of 984 ft.

Family Range

Specimens of the Mayfly Family Metretopodidae

1 Male Dun
1 Male Spinner
9 Nymphs

Discussions of Metretopodidae

S. basale on Clarks Creek, PA
1 replies
Posted by Wiconisco37 on Feb 4, 2009 in the species Siphloplecton basale
Last reply on Jun 10, 2009 by Martinlf
they were discovered on Clarks Creek by a man from halifax, PA
i dont know what their numbers were like thgough

Start a Discussion of Metretopodidae


Mayfly Family Metretopodidae (Pseudo-Gray Drakes)

Genus in Metretopodidae
Genus in Metretopodidae: Metretopus, Siphloplecton
Family Range
Common Name
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