ORDER: EPHEMEROPTERA (Mayflies)
with special reference to those found in Utah
prepared by: original authors?, October 2006
revised by: J. N. Moore, October 2008
Diagnosing Features, adults:
Sail-like triangular forewings held together above body at rest (Fig. 1)
membranous wings with numerous cross veins
hind wings rounded, small or absent
Diagnosing Features, nymphs:
single tarsal claw
three caudal filaments (with notable exceptions) (Fig. 2)
dorsal gills on abdomen
small to medium-sized
soft-bodied
antennae short, small, and setaceous
Habitat: rivers, streams, lakes, and ponds.
Trophic Habits: generally decomposers: shredders, grazers, and collectors.
Development: hemimetabolous.
Preservation: alcohol for nymphs and adults. Adults are fragile – keep in separate vials.
Notes: A winged subimago stage is unique to this order. The subimago molts to become
an adult. Mayflies are effective bioindicators of habitat quality.
Literature Cited:
Merritt R. W., K. W. Cummins, and M. B. Berg, eds. 2008. An introduction to the
aquatic insects of North America, Fourth edition. Kendall/Hunt Publishing Co., Dubuque,
Iowa. 1158 pp.
Edmunds.
Figures:
Fig. 1 – Adult Mayfly, Nelson lab
Fig. 2. Mayfly Nymph, Nelson lab
FAMILY: AMELETIDAE (combmouthed minnow mayfly)
Fig. 1 Pectinate maxilla, J. N. Moore
Morphology (nymphs):
body fusiform and larger than baetids, but antennae are short.
Abdominal segments with small lateral spines.
Outer caudal filaments haired on inner side only.
Pectinate maxilla. (Figure 1)
Ecology: Nymphs generally found in lentic habitats near running water. Most are
collectors and gathers and are classified as swimmers and climbers.
Utah Genera:
Ameletus celer (Utah, Salt Lake), In shallow, slow-moving streams, or clear, still
water. All gills single. Pectinate maxilla. Less commonly collected than
Baetidae.
A. doddsianus: San Juan, Iron.
A. Edmundsi: Salt Lake.
A. oregonensis: Salt Lake, Wasatch.
A. similior: Salt Lake.
A. subnotatus: Wasatch
A. validus: Box Elder, Salt Lake.
A. velox: Box Elder, Davis, Salt Lake, Wasatch.
FAMILY: BAETIDAE (Small Minnow Mayfly)
Morphology (nymphs):
Small mayflies which are fusiform in general morphology (Fig. 1)
Antennae longer than head.
Strong swimmers.
generalized mouthparts for grazing and collecting.
Mount mouthparts and forelegs on a slide for proper generic identification.
Ecology: The nymphs live in diverse habitats from well-oxygenated streams (most
genera) to rather stagnant lentic situations (Callibaetis). They are good swimmers.
These are often the most abundant mayflies in a stream.
Utah Genera:
Baetis bicaudatus: Salt Lake, Wasatch. Middle tail shorter than outer ones.
Abundant in running waters.
Baetis tricaudatus: Wasatch.
Camelobaetidius wareni:Uintah, Washington.
Diphetor hageni: Box Elder, Cache, Tooele, Utah, Wasatch, Summit, Sanpete,
Iron.
Fallceon quilleri: Iron.
Procloeon oreophilum: Cache.
Pseudocloeon apache: Wayne.
Callibaetis: Abundant in ponds. Gills with two flaps, larger one ventral.
Centroptilum: Not common. Inhabits streams. Flap of gill dorsal.
Pseudocloeon turbidum McDunnough: Uncommon, Logan, Duchesne, Green,
Sevier and Santa Clara Rivers, probably elsewhere in larger or warmer rivers.
Dactylobaetis cepheus Traver and Edmunds: Uncommon in medium or large
rivers, e.g., Green, White and Virgin. May to July.
Paracloeodes: may occur in Utah. In Green River at Green River (city),
Wyoming.)
Centroptilum conturbatum (McDunnough): Locally common, generally
uncommon in montane streams, rarely in mountain ponds, widespread. Spring
through September. Records from May to August.
FAMILY: BAETISCIDAE (Armored Mayfly)
Morphology (nymphs):
Thoracic notum enlarged to form heavy shield
Gills enclosed beneath shield. (Fig. 4)
Ecology: Found in shallows of sandy streams. Mass emergences.
Utah Genera:
Unknown.
FAMILY: CAENIDAE (Small Squaregilled Mayfly)
Fig. 3 – dorsal position of square operculate gills
Morphology (nymphs):
Small to medium mayflies which are stocky in general morphology.
square operculate first pair of gills (on the dorsum of the second segment of
abdomen).
Similar to Leptohyphidae in general appearance.
Adults fall and die with their wings spread when attracted to blacklights.
Ecology: The nymphs can live in rather stagnant lentic habitats.
Utah Genera:
Brachycerus tuberculatus: Wasatch.
Brachycerus sp. (probably prudens McDunnough). Rare, in Green River. June.
Caenis sp: Widespread. In silty bottom of slow streams and ponds.
Caenis sumulans McDunnough. Locally abundant in ponds, marshes and lakes
up to 7,600 feet, widespread (i.e., duck marshes to Strawberry Reservoir). June
to September.
Figures:
FAMILY: EPHEMERIDAE (Burrowing Mayfly)
Morphology (nymphs):
Prominent mandibular tusks curved upward, no spines on top surface.
Feathery gills on abdomen fringed with long hairs
Ecology: Nymphs live in silty rivers, ponds, and lakes where they burrow into flocculent
substrate. The often have huge mass emergences.
Utah Genera:
Hexagenia, In mud bottom of still or slow moving water, frontal process simple.
Ephemera, In mud bottom of still or slow moving water, frontal process forked.
Ephemer simulans Walker. One known locality, common at Uintah River at Fort
Duchesne. All seasons, adults in July.
Hexagenia limbata Seville. Ucommon in rivers and canals in northern Utah, but
common in Bear River near Randolph and Uintah River at Fort Duchesne. All
seasons, with adults from June to October.
FAMILY: EPHEMERELLIDAE (Spiny Crawler Mayfly)
Fig 1. Spikey forefemora, Nelson Lab
Fig 2. Dorsal gill plates of drunella grandis, J. N. Moore
Morphology (nymphs):
Squat, small to medium
Often with extraordinary patterns of spines on body, especially abdomen.
Gills absent on abdominal segment 2
Plate-like dorsal gills of the abdomen. (figure 2)
Ecology: The nymphs live in various lotic habitats but are more common in welloxygenated streams of high gradient. They are slow moving clingers and sprawlers
which exploit a wide range of function feeding groups.
Utah Genera:
Attenella margarita (Needham) Duchesne, Summit. Uncommon in a few middle
sized rivers, often withTimpanoga. From 5500 to 7500 feet elevations. July to
September.
Drunella doddsi: Salt Lake, San Juan. abdomen with ventral sucker, head with
notches for antennae. Common in cool streams.
Drunella grandis grandis: Cache, Uintah, Beaver, Washington. Sometimes very
abundant in middle sized or large trout streams throughout Utah.
Drunella coloradensis (Dodds): abundant in small or middle sized streams.
Ephemerella inermis (Eaton): Salt Lake, Morgan, Utah, Duchesne, Uintah,
Daggett, Grand, Emery, Sanpete, Kane, Washington. occurs from 8000 feet
down to large silted rivers. All seasons.
Ephemerella infrequens (McDunnough): Box Elder, Salt lake, Utah, Sanpete,
Wasatch, Duchesne, Uintah. Occurs at higher altitudes and colder streams.
Serratella tibialis (McDunnough): Wasatch, Summit, Uintah. Common species
at middle altitudes in most of Utah. June to September.
Timpanoga hecuba hecuba (Eaton): Wasatch, Summit, San Juan. Found in
middle sized rivers such as the middle Duchesne, Provo, and Weber Rivers.
Emerges August-September, larvae all summer.
FAMILY: HEPTAGENIIDAE (Stream Mayfly)
Fig. 1 –Epeorus – note absence of caudal filament Fig. 2 - Rhrithrogena ventral disk
Morphology (nymphs):
dorsoventrally flattened
laterally projecting flattened legs help maintain position in swift current.
Many have flattened heads with expansive clypeolabral complex.
Ecology: The nymphs can live in a wide variety of lotic habitats and can regularly be
found in more lentic habitats as well.
Utah Genera:
Cinygmula par (McDunnough): Salt Lake. On rocks in clear streams. Gills with
minute filament at base, no tuft. Abundant in montane streams and rocky bottom
streams.
Heptagenia elegantula (Eaton): Uintah, San Juan. Abundant in medium to large
rivers.
Heptagenia solitaria (McDunnough): Summit, Duchesne, Uintah.
Nixe criddlei (McDunnough): Salt Lake, Utah, Washington, San Juan. Abundant
from high mountains to low elevations.
Stenonema terminatum terminatum (Walsh): Utah. Utah. Uncommon, known
only from Jordan River and associated canals. May occur in lower Ogden, Bear,
Logan Rivers, etc. Larvae (nymphs) May to September.
Rhithrogena robusta (Dodds) cold streams.
R. morrisoni (Banks):
R. hageni (Eaton): middle sized trout streams
R. undulate (Banks): in warm waters (marginal to brown tout or with warm
water fish). All seasons.
Leucrocuta petersi (Allen): Known from the Whiterocks, Uintah and Duchesne
Rivers in the Uintah Basin (formerly Heptagenia petersi).
Epeorus longimanus: Larvae (nymphs) are keyed by Edmunds and Allen (1964).
All seasons. Abundant in montane streams, widespread throughout Utah.
E. albertae (McDunnough):
E. deceptivus (McDunnough):
Anepeorus rusticus (McDunnough): Rare, one record from Green River at Split
Mountain, Doinsaur National Monument. Emergence in July.
Pseudiron centralis (McDunnough): Rare, from Green River. June to September,
emergence in August. Landa and Soldan (1985) have transferred this genus to a
montypic subfamily of the family Siphlonuridae.
FAMILY: ISONYCHIIDAE (Brushlegged Mayfly)
Fig. 1 – fusiform shape
Fig. 2 – long leg hairs
Morphology (nymphs):
fusiform body
front legs with long hairs
gills small, flat, dorsal on 2-7 segments
Ecology: In sandy areas of rivers and streams. Generally lotic. Clingers and burrowers..
Utah Genera:
Isonychia campestris
FAMILY: LEPTOHYPHIDAE
Fig. 1 – stocky form
Morphology (nymphs):
Fig. 2 – triangular operculate gills
small to medium
stocky in general morphology.
triangular operculate first pair of gills (on the dorsum of the second segment
of abdomen). The opercula meet at their bases, sometimes overlapping, but the apices
diverge. These opercula cover the remaining gills. Similar to Caenidae in general
appearance.
Ecology: The nymphs can live in a wide variety of lotic habitats and can be regularly
found in more lentic habitats as well. In small to large streams with fine sand and
gravel.
Utah Genera:
Tricorythodes Minutus (Traver): Salt Lake, Washington. Abundant in warmer
streams throughout Utah. Debris attached all over body, forefemoral spines in
clusters.
T. edmundsi (Allen): occurs in the Green River. All seasons.
Leptohphes apache (Allen): Uncommon. Virgin River in Zion National Park.
FAMILY: LEPTOPHLEBIIDAE (Prong-gilled Mayfly)
Fig. 1 – flattened head
Fig. 2 – forked gills
Morphology (nymphs):
Similar to heptageniids, but are more slender.
Forked gills, tapered and long, sometimes with fringe on each fork
Some have flattened heads with expansive clypeolabral complex.
Ecology: The nymphs live in well-oxygenated lotic habitats.
Utah Genera:
Traverella albertana (McDunnnough): Washington, Kane, San Juan, Emery,
Uintah. Abundant in White, Green and Colorado Rivers and warmer tributaries.
July through October.
Paraleptophlebia heteronea (McDunnough): In rather slow water or eddies on
decaying leaves, etc. Common in montane streams, widespread throughout Utah
P. memorialis (Eaton) (= pallipes Hagen),
P. debillis (Walker):
P. packi (Needham): All seasons, emerge June through October.
Leptophlebia gravastella (McDunnough): Locally common, Green River,
Uintah River, lower Strawberry River, others of Uintah Basin. Occurs only in
spring season, May and June emergence.
Choroterpes albiannulata McDunnough. Locally common in warmer Colorado
River drainage streams, August and September.
Thraulodes gonzalesi Traver and Edmunds. One specimen only form Green
River at Dinosaur National Monument. July.
FAMILY: OLIGONEURIIDAE
Morphology (nymphs):
fusiform body,
front legs with long hairs
gills small, flat, dorsal on 2-7 segments, ventral on segment one
Ecology: In sandy areas of rivers and streams. generally lotic. Clingers and burrowers.
Utah Genera:
Homoeoneuria alleni (Pescador & Peters): Grand, Kane. VERY RARE in big
rivers of eastern Utah such as Colorado River (Westwater Canyon) and Escalante
River, sand inhabitant. June to August.
Lachlania (Edmunds): (Name will probably fall as a junior synonym of
saskatchewanensis Ide). Common locally, known only from Green and Colorado
Rivers. July through September.
Figures:
FAMILY: POLYMITARCYIDAE (Pale Burrower Mayfly)
Fig. 1 – feathery gills
Fig. 2 Mandibular tusks
Morphology (nymphs):
Front legs heavy - used for digging.
Generally light colored with feathery gills on abdomen, ringed with long hairs.
Prominent mandibular tusks not curved upward, spines on top surface.
(Fig. 2)
ventral apex of the hind tibia is rounded.
Adults have small legs incapable of supporting them to perch.
Ecology: The nymphs live in silty rivers, ponds, and lakes where they burrow into the
flocculent substrate. Search in clay banks on the forks of a large stream or river. They
often have huge mass emergences.
Utah Genera:
Ephoron album (Say). In lowland, silty streams and canals of northern Utah.
Locally abundant in warmer rivers and canals in northern Utah. May to
September; emerges August-September.
FAMILY: SIPHLONURIDAE
Morphology (nymphs):
Fusiform shape comparable to baetids
Antennae short compared to baetids
Gills oval or subtriangular
Maxilla without pectinate spines.
Forelegs without hairs
Ecology: The nymphs live in silty rivers, ponds, and lakes where they burrow into the
flocculent substrate. Search in clay banks on the forks of a large stream or river. They
often have huge mass emergences.
Utah Genera:
Ephoron album (Say). In lowland, silty streams and canals of northern Utah.
Locally abundant in warmer rivers and canals in northern Utah. May to
September; emerges August-September.