Speckled Dun. Callibaetis sp.
Callibaetis
Nymph 5
Size: Mature nymph 6-12mm long (excluding tails).
Body: Body color pale tan, olive, or olive brown; heart-shaped gills on abdominal segments 1-7.
Tails: Three tails equal length, fringed with fine hairs.
Other: Antennae long, 2-4 times the length of the width of the head.
Nymph Look Alikes 5
Nymph Look Alikes:Callibaetis nymphs are most likely to be confused with Cloeon dipterum (Pond
Olive), Siphlonurus spp. (Black Drake), or Ameletus spp. (Brown Drake) nymphs. Both Siphlonurus and
Ameletus nymphs have short antennae (less than twice the head width), which readily distinguish them
from the long antennae (2-4 times head width) of Callibaetis. C. dipterum nymphs are more difficult to
distinguish from Callibaetis without the aid of magnification, as the lack of hind wing pads and dorsally
folded gill flaps (versus ventrally folded in Callibaetis) are characteristics of C. dipterum nymphs lacking in
Callibaetis.
DUN (SUBIMAGO) 5
Size: 6 - 12 mm.
Body: Typically brown to grey.
Wings: Wing color gray to brown with pale areas along venation; Hind wings quite small and can be hard to see.
Tails: Two tails.
SPINNER (IMAGO) 5
Size: 6 - 12 mm.
Body: Grey to almost black.
Wings: CLear, often with speckled dark markings near the leading edge. Hind wings quite small and can be hard to see.
Tails: Two tails.
Dun/Spinner Look Alikes 5
Dun/Spinner Look Alikes:Callibaetis adults will most likely be confused with Siphlonurus adults. The
small hind wing of Callibaetis, along with its wing color (light colored veins on duns and speckled dark
markings on spinners), and body size, will quickly distinguish it from Siphlonurus. Callibaetis adults may
also be confused with those of Cloeon dipterum, another still-water inhabitant belonging to the Baetidae
family. While C. dipterum may show some mottling along the leading margin of the forewing, this species
lacks hind wings, allowing for easy separation from Callibaetis adults.
Habitat & Distribution 5
Callibaetis are found in lakes, ponds, and slower-moving sections of lower-gradient
rivers. While at least four species are known to occur in New England (C. ferrugineus,
C. fluctuans, C. pallidus, and C. pretiosus), only C. ferrugineus is recognized as a
common hatch for anglers.
Life Cycle - Emergence 5
Callibaetis are multibrooded, producing two or three generations per year, depending on
climatic conditions. Hatching occurs intermittently from spring into the early fall, with
two or three peaks occurring during this period.
Mature nymphs swim to the water’s surface where the duns emerge. Dun emergence
can occur from mid-morning to late afternoon depending on weather conditions, with
overcast days producing larger and longer hatches. Large numbers on the surface is
common.
After molting to the spinner stage, spinners mate in the air, and then females return to
streamside foliage for up to five days while the eggs develop. Females return to the
water from mid-afternoon to late evening to lay their eggs, which hatch almost
immediately.
Massachusetts: May through September, with several peaks depending on weather
and water temperatures.
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.
Callibaetis sp.
Taxonmoic level
Taxonomic Name
Feature
Degree of difficulty
Order
Ephemeroptera
Wing Shape
1
Family
Baetidae
two tails,detached intercolinary veins in wing.
3
Genus
Callibaetis
Small hind wing, dun wing grey to brown, body brown to grey, spinner wing haylene with leading edge speckaled or dark, body grey to black.
3.5
Species
sp.
May-September. Many species.
NA
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, some rights reserved (CC BY-NC-ND), http://www.flickr.com/photos/79718069@N00/8679943721/
- (c) David Reed, some rights reserved (CC BY-NC-SA), https://www.flickr.com/photos/60382879@N06/5560030722/
- (c) Jerry Schoen, some rights reserved (CC BY-NC-ND), http://www.flickr.com/photos/79718069@N00/8708123750/
- (c) Curtis Fry, some rights reserved (CC BY-NC), https://www.flickr.com/photos/fritography/13977014009/
- (c) Jay Aylward, some rights reserved (CC BY-SA)
