Mayflies
Order: Ephemeroptera
Life Cycle
• Hemimetabolous (egg, naiad, adult)
– Naiad: aquatic, gill-breathing nymph
– Nymph: larva of an insect without a pupal stage
• 1-3 generations / year; 12-50 molts!
• Subimago stage (“duns”)
• Short-lived adult stage (“spinners”)
General Morphology
Naiads:
Large eyes
Chewing mouthparts
Gills on abdomen
Usually 3 tails
Adults:
Soft-bodied
FW large, triangular, veined
Elongated forelegs, tails
Naiad Morphology
• Well developed eyes
• Slender antennae
• Well-developed legs,
with one claw
• Gills (abdomen sides)
• Fore-wing pads may be
present
• Usually 3 caudal
filaments (tails)
Adult Morphology
•
•
•
•
Elongate, very soft
FW large, many veins
HW small or absent
Wings above body at
rest
• Mouthparts vestigial
• Fore-legs very long
• 2-3 long tails
Systematics
• 2 suborders: Schistonota
(“Splitbacks”) and Pannota
(“Fusedbacks”), refers to wing pads
• 3 superfamilies in each suborder
• 17 families
• Characters used include gill structures,
mouthparts, hairs/spination: these
change with age!
Suborder Schistonota
“Splitback Mayflies”
• Larval fore wing pads free for at
least half of the pad length
• Thorax usually slim and delicate
• Gill series usually well developed
on sides of abdomen
• Active and diverse mayflies
Suborder Schistonota
Superfamilies
Baetoidea (6 families)
Leptophlebioidea (1 family)
Ephemeroidea (5 families)
Superfamily Baetoidea
Families:
Siphlonuridae (“Primitive Minnow”)
Metretopodidae (“Cleftfooted Minnow”)
Ametropodidae (“Sand Minnow”)*
Baetidae (“Small Minnow”)
Oligoneuridae (“Brushlegged”)
Heptageniidae (“Flatheaded”)
* Western. 3 species, not covered here.
Siphloneuridae
(“Primitive Minnow Mayflies”)
•
•
•
•
Streamlined
Long axis of head vertical
Fore legs w/o hairs
Platelike gills oriented
dorsally
• Sharp spines on posterior
abd. Segments
Ameletus sp.
Metretopodidae
(“Cleftfooted Minnow Mayflies”)
• Strong swimmers
• Medium/large rivers
• 2 claws on foreleg
Siphloplecton basale
Baetidae
(“Small Minnow Mayflies”)
•
•
•
•
Small, 9-10 mm
Variety of habitats
Good swimmers
Some tolerate
polluted water
• Some with 2 tails!
Callibaetis (left)
Pseudocloeon (right)
Baetidae
• Fall emergence in
some species
• Note rounded 9th
abdominal segment
Baetis longipalpus
(Antennae more than
twice width of head)
Subimago Baetis tricaudatus
• Shorter front legs
• Dull wings
• Fringe of ciliated
hairs on wings
• Dun, “little iron blue
quill”
Adult Baetis tricaudatus
• Longer front legs
• Brighter colors
• Spinner, “blue
winged olive
(applies to Baetids
in general)”
Oligoneuridae
(“Brushlegged Mayflies”)
• Streamlined shape
• Filter feed with hairs
on front legs
• Swift currents
Isonychia sadleri
Isonychia Filter Feeding
Isonychia bicolor
“Leadwing Coachman,”
“Mahogany Dun.”
Isonychia sadleri
imago
Heptageniidae
(Flatheaded Mayflies)
• Greatly flattened
head, legs
• Clinging under rocks
• Often very long tails
Stenonema rubrum
(Note unique 7th gill
structure)
Heptageniidae
(7th abdomimal gill)
S. rubrum
Heptageniidae
Stenacron interpunctatum
• Subimago called
“Light Cahill”
• 7-12 mm, excluding
tails, legs
• May-September
• Note relatively short
legs of subimago
Heptageniidae
S. Rubrum imago
Heptageniidae
• Cup-shaped to cling
• Bright red gill color
(Ventral view)
Rhithrogena sanguinea
Superfamily Leptophlebioidea
Family
Leptophlebiidae (“Pronggills”)
Leptophlebiidae
(“Pronggills”)
• Gills on segs. 1-6 or 1-7
• Gills double or forked
• Prefer crevices
Leptophlebia sp.
Leptophlebiidae
• Subimago called
“dark blue quill”
• Small (6-8mm
excluding tails, legs)
• August-October
• Note long legs of
imago
Paraleptophlebia debilis
imago
Superfamily Ephemeroidea
Families:
Behningidae (“Tuskless Burrowers”)*
Potatamanthidae (“Hacklegills”)
Polymitarcyidae (“Pale Burrowers”)
Ephemeridae (“Common Burrowers”)
Palingeniidae (“Spinyheaded Burrowers”)**
*Southeast U.S. only
**South only
Potamanthidae
(“Hacklegills”)
• Somewhat like
Heptageniidae,
but…
• Gills unique,
laterally oriented
• Tusks, curve inward
Polymitarcyidae
(“Pale Burrowers”)
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•
•
•
Larvae in silt, stream banks
Adult with nonworking legs
Sexually mature subimago
Subfamily id uses frontal
processes
Polymitarcyinae
Ephoron sp.
Campsurinae
Ephemeridae
(“Common Burrowers”)
• Large, 12-32 mm
• Tusks lack spines,
curve up & out
• Burrow in silt-sand
in rivers or lakes
Ephemera sp.
Ephemera sp.
Hexagenia sp.
Hexagenia limbata
(“Michigan Caddis”)
Ephemera guttulata subimago
(“Green Drake”)
(18-21 mm + tails)
Suborder Pannota
“Fusedback Mayflies”
• Naiad with wing pad fused
to thorax for at least half of
pad length
• Thorax robust
• Gills lay on abdomen
• Operculate (covering) gills
Suborder Pannota
Superfamilies
Ephemerelloidea (2 families)
Caenoidea (2 families)
Propistomatoidea (1 family)
Superfamily Ephemerelloidea
Families:
Ephemerellidae (“Spiny Crawlers”)
Tricorythidae (“Little Stout Crawlers”)
gills
Ephemerellidae
(“Spiny Crawlers”)
• 5-15 mm + tails
• dorsal spines on head,
thorax, abdomen
• No gills on segment 2
• Gills lie on abdomen
Serratella sp. (left)
Timpanoga sp. (right)
Tricorythidae
(“Stout Little Crawlers”)
• 3-10 mm + tails
• Hind wing pad
absent or minute
• Gills on seg. 2-6
• Gills on 2 are
triangular and
operculate
Superfamily Caenoidea
Families:
Neoephemeridae (“Large Squaregills”)
Caenidae (“Small Squaregills”)
Caenidae
(“Small Squaregills”)
• Widespread and
common in east
• Small, 3-4 mm + tails
• No hind wing pads
• Operculate gills
overlap slightly
Caenis simulans
Superfamily Propistomatoidea
Family
Baetiscidae (“Armored Mayflies”)
Baetiscidae
(“Armored Mayflies”)
• Banks of medium
streams
• Striking thoracic
shield