Eastern Sulphur - Ephemerella Invaria
Ephemerella invaria
NYMPH 3
Size: 7- 10 mm
Body: Rounded in cross section (not flattened); color olive brown, red brown, to black brown, sometimes with various lighter markings such as small spots or partial bands across some abdominal segments
Legs: Light brown/tan with medium brown banding
Tails: Three tails
Nymph Look Alikes 3
Without magnification, nymphs of the genus Ephemerella can be difficult to identify
to species. The three common Ephemerella species in central New England include E. subvaria, E. invaria, and E. dorothea. Both E. subvaria and E. invaria are larger than E. dorothea when mature, and E. dorothea lacks short, paired spines present on the abdominal segments of both E. subvaria and E. invaria. Furthermore, nymphs of other genera within the Ephemerellidae family generally resemble E. invaria in shape, size, and coloration. When possible, mature specimens should be collected for more reliable identification under magnification.
DUN (SUBIMAGO) 3
Size: 8 to 11 mm (males slightly smaller than females)
Body: Yellow to cream, often with light brown markings on top of abdomen
Wings: Light grey
Tails: Three tails, light brown and barred
SPINNER (IMAGO) 3
Size: 8 to 10 mm
Body: Males are reddish brown, while females are tan/cream
Wings: Clear wings (hyaline)
Tails: Three tails
Dun/Spinner Look Alikes 3
Ephemerella invaria is similar to E. dorothea, but E. dorothea is smaller (5-7 mm versus 8-10 mm).
HABITAT & DISTRIBUTION 3
Ephemerella invaria is one of the more common mayflies in trout streams and small
rivers across the eastern United States. Able to tolerate a range of temperature and
flow conditions, E. invaria is widespread and often abundant in eastern streams.
Nymphs occur in a variety of habitats, from slow-flowing pools and runs to fast riffles, although they will tend to be most numerous in medium- to fast-flowing reaches.
LIFE CYCLE - EMERGENCE 3
Anglers eagerly await the “sulphur” hatches of early summer. Both E. invaria and E. dorothea are known by this common name. In addition to size difference between the two species (see “Lookalikes” section above), emergence timing also differs, but often partially overlaps. E. invaria is the first of the two species to hatch; emergence activity begins when water temperatures reach the mid-fifties. Nymphs are known to crawl into the shallow stream margins, where they will swim with a slow wriggling motion to the surface, rendering emerger patterns of this species quite effective.
Following emergence, duns are said to molt and return to the stream as spinners within a day. Information on the reliability of a spinner fall of this species is conflicting; while some suggest that only females fall spent and do so inconsistently, others state that both genders fall spent.
Massachusetts: Late May/early June into July, depending on weather and water
temperatures. Some have been seen on the Swift River as late as August.
Taxonomy 4
Comments: Ephemerella rotunda, Ephemerella vernalis, Ephemerella feminina, Ephemerella fratercula, Ephemerella inconstans, Ephemerella choctawhatchee, Ephemerella simila, and Ephemerella floripara are all junior synonyms of Ephemerella invaria (Jacobus and McCafferty, 2003).
Degree of difficulty 5
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 invaria
Taxonmoic level
Taxonomic Name
Feature
Degree of difficulty
Order
Ephemeroptera
Wing Shape
1
Family
Ephemerellidae
3 tails/time/of year/body coloration.
3
Genus
Ephemerella
3 tails/time/of year/body coloration
3
Species
invaria
8-11mm, yellow to cream, with light brown markings on top of abdonomen, 3 tails lightly barred. Spinner:males reddish brown/ females tan/cream.
3.5
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
- (c) Jerry Schoen, all rights reserved, uploaded by Jerry Schoen
- (c) Anita, some rights reserved (CC BY-NC-SA), http://www.flickr.com/photos/61897811@N00/4702247734
- Adapted by Jay Aylward from a work by (c) Jerry Schoen, some rights reserved (CC BY-SA)
- Adapted by Jay Aylward from a work by (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/14552128
- (c) Jay Aylward, some rights reserved (CC BY-SA)
