Hendrickson/Red Quill

Ephemerella subvaria

NYMPH 8

Size: 8-11 mm.
Body: Rounded in cross section (not flattened); color olive brown, red brown, to black brown, often with lighter band across abdomen.
Legs: Light brown/tan with darker brown banding.
Tails: three tails.

Nymph Look Alikes 8

Ephemerella subvaria nymphs are easily confused with those of Ephemerella invaria (Sulphur or Pale Evening Dun). Only E. subvaria has the distinct banding on the abdomen, but this does not occur on all individuals. E. subvaria nymphs are usually also larger when fully mature.

DUN (SUBIMAGO) 8

Size: Body size: 8-12 mm (males slightly smaller than females)
Body: Grey-brown to tan-brown; females generally lighter than males
Wings: Large hind wings; uniform medium grey
Tails: Three tails (all same size)

SPINNER (IMAGO) 8

Size: Body size: 8-12 mm (males slightly smaller than females)
Body: Dark reddish-brown
Wings: Large hind wings; hyaline (clear) wings
Tails: Three tails (all same size)

Dun/Spinner Look Alikes 8

Quill Gordons (Epeorus pleuralis), while slightly smaller and daintier, resemble E. subvaria duns and spinners. They can readily be distinguished from one another by the number of tails (only two on the former). Hendrickson adults may also be confused with those of the genus Leptophlebia (the Black Quill), which is also an early season hatch (but far less often encountered than the Hendrickson). The Black Quill can be distinguished from the Hendrickson by the presence of a middle tail that is noticeably shorter than the outer filaments. Also note the distinct wing venation on the Black Quill that is not evident on the Hendrickson.

HABITAT & DISTRIBUTION 8

Ephemerella subvaria is a common, often abundant, mayfly on many northeastern trout streams. The nymphs inhabit well-oxygenated riffles and runs, from which they emerge in the late spring. The nymphs are said to avoid areas of fluctuating water temperatures.

LIFE CYCLE - EMERGENCE 8

Hendricksons are among the first mayflies to hatch each spring, often following the Quill Gordons (Epeorus pleuralis) by only a few weeks. In central New England, hatching may begin as early as April and go on for several weeks, sometimes into early June, dependent on weather conditions. The nymphs emerge by swimming to the surface where they will writhe to free themselves of their nymphal shuck. Emergers and newly hatched duns may ride on the water’s surface for some distance, making for easy and enticing quarry for feeding trout. Information relating to the behavior and importance of the spinners to the fly angler is conflicting. While most sources suggest that females drop their eggs to the water from high in the air, minimizing their importance as fish food until they drop spent in the later evening, a few sources suggest that the females do lay their eggs while laying on the water.

Massachusetts: April into early June, depending on weather and water temperatures.

Degree of Difficulty 9

This table is meant to help users get an idea of how easy/hard it is to ID this species to any taxonomic level, and to give an idea of the characters (or features) that are important to accurately identifying a specimen. As a general guideline, these degree of difficulty levels translate to the type of effort needed to reliably ID a specimen to that taxonomic level, as long as the associated features are confirmed. Of coarse there will/may be exceptions to these general rules.

Ephemerella subvaria

Taxonmoic level
Taxonomic Name
Feature
Degree of difficulty


Order
Ephemeroptera
Wing Shape
1


Family
Ephemerellidae
3 uniform tails, needs to be under scope to check for tails.
3.5


Genus
Ephemerella
needs to be under the scope or photo to check tails, could be confused with leptophlabia (black quill)
3.5


Species
subvaria
8-12 mm, grey-brown to brown-tan, large hind wings, 3 even non-barred tails. April- early June, range is a factor and a good photo is needed
4

Degree of Difficulty

Degree of Difficulty
Description

1
Can be ID’d on the wing or water.

2
A specimen in the hand can be ID’d.

3
Can be ID’d by studying a decent photo of the specimen.

4
Can be ID’d by studying a captured & preserved specimen, usually under some magnification.

5
Proper ID requires study of preserved specimen under magnification, usually looking for some feature that can be difficult to confirm. Usually requires training or confirmation from a professional.

Sources and Credits

  1. (c) jerry2000, all rights reserved, uploaded by Jerry Schoen, http://www.inaturalist.org/photos/845010
  2. (c) Mike Cole, all rights reserved, uploaded by Jerry Schoen, http://www.inaturalist.org/photos/855886
  3. (c) Dan Trela, all rights reserved, uploaded by Jerry Schoen, http://www.inaturalist.org/photos/855887
  4. (c) Mike Cole, all rights reserved, uploaded by Jerry Schoen, http://www.inaturalist.org/photos/855888
  5. (c) Mike Cole, all rights reserved, uploaded by Jerry Schoen, http://www.inaturalist.org/photos/855890
  6. (c) Mike Cole, all rights reserved, uploaded by Jerry Schoen, http://www.inaturalist.org/photos/855889
  7. (c) jaylward, all rights reserved, uploaded by Jay Aylward, http://www.inaturalist.org/photos/1614220
  8. Adapted by Jay Aylward from a work by (c) Jerry Schoen, some rights reserved (CC BY-SA)
  9. (c) Jay Aylward, some rights reserved (CC BY-SA)

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