Minnesota Mayflies

     
 
Order Ephemeroptera
 
 

Ephemeroptera is the order of small to medium-sized flying insects known as mayflies. They have elongated, very soft bodies. The forewings are triangular, very large, and have many veins. They are held together above the body when at rest. The hindwings are small and round, or in some species missing. The abdomen has 2 or 3 hair-like tails. The antennae are short, bristle-like, and inconspicuous. The last part of the leg (tarsus), corresponding to the foot, has 3 or 5 segments. The mouthparts are small, poorly developed, and non-functional. Adults often emerge in large numbers, sometimes piling up on the shore. Many species engage in swarming flights, where they fly up and down in unison. They do not feed and seldom live more than 1 or 2 days.

The young, called nymphs, are aquatic. They have leaf-like gills along the sides of the abdomen, and 3 hair-like tails at the end of the abdomen. Most mayfly nymphs develop in streams and rivers, some develop in lakes and ponds. The feed on small aquatic organisms and organic debris. They swim to the water surface or crawl onto emergent vegetation or rocks to complete the second-to-last molt. This subadult stage has functional wings and is called a subimago. They fly to nearby vegetation and molt one last time, emerging as adults. Mayflies are unique as the only insect that molts again after developing functional wings.

Mayflies are an important food source for freshwater fish. Fly fisherpersons use mayflies as bait.

There are more than 3,000 species in more than 400 genera in 42 families of mayflies worldwide. There are 611 species in 59 genera in 21 families in North America north of Mexico. There are estimated to be 100 to 119 species in Minnesota.

 
 
giant mayfly
Photo by Luciearl
         
 
Recent Additions
 
 

Giant mayfly

 
 

Giant mayfly (Hexagenia limbata) is a large “common burrower” mayfly. It is very widespread, occurring in the United States and southern Canada from the east coast to the Great Plains and on the west coast. It is mostly absent from the desert and mountain regions in the west. It is the most common mayfly in the Midwest, and is common in Minnesota.

Larvae are found in organic, silty or mucky bottoms of lakes, ponds, and rivers, usually about three meters below the water surface. They feed on organic material suspended in the water. Immature adults are found on trees and bushes on shores near the bodies of water from which they emerged. Adults are found flying in swarms over land near the water body. They do not feed and live from just a few hours to a few days. Emergences are synchronized and can produce swarms so large that they can bee seen by weather satellites. Snow plows are sometimes used to clear dead mayflies off of roads.

Giant mayfly is said to be the largest mayfly in the United States. It can be more than one inch in length, not including two hair-like “tails” that can be equally long. The body may be yellow, yellowish-brown, brown, or even white. Aside from its very large size, giant mayfly is identified by the wing veination, and by the four-segmented end part (tarsus) of the hind leg.

  giant mayfly  
    Photo by Luciearl  
       
       
       
       
       
       
       
       
       
       
 

Pond olive

 
 

Pond olive (Cloeon dipterum) is a small minnow mayfly. It occurs throughout Europe, where it is native, and in Asia and North America, where it has been introduced. The earliest North American record is from Illinois in 1953. It is now widespread across the continent. In the United States it is currently mostly restricted to the northeast and to Washington state. It is rare in Minnesota. Nymphs are found mostly in ponds, but also in the shallow margins of lakes and in slow areas of rivers and streams. They feed on algae, small aquatic organisms, and organic debris. Adults are found on vegetation near ponds. They do not feed and seldom live more than 1 or 2 days.

Adults are reddish-brown and have 2 very long hair-like tails at the end of the abdomen. The compound eyes on the female are on the sides of the head. On the male the compound eyes have additional large, orange, turban-like parts that meet at the top of the head. These adaptations are said to allow the male to isolate in a swarm females that are not yet paired with another male. Some authors say that pond olives have no hindwings. Carl Linnaeus in 1761 described the hindwings as “hardly present.”

  pond olive  
    Photo by Alfredo Colon  
       
       
       
       
       
       
       
       
       
       
         
 
Other Recent Additions
 
 

 

     

 

 

 

                 
 

This list includes only mayflies that have been recorded in Minnesota, but not all of the mayflies found in Minnesota.

 
                 
 
         
Profile Photo Video    
       

Aphrodite’s flat-headed mayfly (Leucrocuta aphrodite)

       

brown drake (Ephemera simulans)

       

brown small minnow mayfly (Baetis brunneicolor)

       

brush-legged mayfly (Isonychia velma)

       

cloudy prong-gilled mayfly (Leptophlebia nebulosa)

       

common small minnow mayfly (Baetis tricaudatus)

       

common spiny-headed burrowing mayfly (Pentagenia vittigera)

       

confused small minnow mayfly (Acentrella turbida)

       

dark cahill (Stenonema femoratum)

       

early brown spinner (Leptophlebia cupida)

       

emergent mayfly (Hexagenia bilineata)

       

fragile prong-gilled mayfly (Paraleptophlebia debilis)

Profile Photo Video  

giant mayfly (Hexagenia limbata)

       

golden drake (Anthopotamus distinctus)

       

Hebe’s flat-headed mayfly (Leucrocuta hebe)

       

lake hex (Hexagenia atrocaudata)

       

Laurentian armored mayfly (Baetisca laurentina)

       

maculated small square-gilled mayfly (Sparbarus maculatus)

       

mahogany dun (Isonychia bicolor)

       

march flat-headed mayfly (Maccaffertium vicarium)

       

modest flat-headed mayfly (Maccaffertium modestum)

       

northern small square-gilled mayfly (Caenis diminuta)

       

northern summer mayfly (Siphlonurus alternatus)

       

orange cahill (Stenacron interpunctatum)

Profile Photo Video   pond olive (Cloeon dipterum)
       

pretty small minnow mayfly (Callibaetis pretiosus)

       

red speckled dun (Callibaetis ferrugineus ferrugineus)

       

ringed small minnow mayfly (Acentrella parvula)

       

Rock Island small minnow mayfly (Labiobaetis propinquus)

       

small square-gilled mayfly (Cercobrachys etowah)

       

southern flat-headed mayfly (Maccaffertium mexicanum)

       

stream mayfly (Nixe kennedyi)

       

terminal flat-headed mayfly (Maccaffertium terminatum)

       

Walker’s tusked sprawler (Anthopotamus verticis)

       

white fly (Ephoron leukon)

       

yellow-streaked small minnow mayfly (Baetis flavistriga)

 

Acentrella parvula (ringed small minnow mayfly)

Acentrella turbida (confused small minnow mayfly)

Anthopotamus distinctus (golden drake)

Anthopotamus verticis (Walker’s tusked sprawler)

Baetis brunneicolor (brown small minnow mayfly)

Baetis flavistriga (yellow-streaked small minnow mayfly)

Baetis tricaudatus (common small minnow mayfly)

Baetisca laurentina (Laurentian armored mayfly)

Caenis diminuta (northern small square-gilled mayfly)

Callibaetis ferrugineus ferrugineus (red speckled dun)

Callibaetis pretiosus (pretty small minnow mayfly)

Cercobrachys etowah (small square-gilled mayfly)

Cloeon dipterum (pond olive)

Ephemera simulans (brown drake)

Ephoron leukon (white fly)

Hexagenia atrocaudata (lake hex)

Hexagenia bilineata (emergent mayfly)

Hexagenia limbata (giant mayfly)

Isonychia bicolor (mahogany dun)

Isonychia velma (brush-legged mayfly)

Labiobaetis propinquus (Rock Island small minnow mayfly)

Leptophlebia cupida (early brown spinner)

Leptophlebia nebulosa (cloudy prong-gilled mayfly)

Leucrocuta aphrodite (Aphrodite’s flat-headed mayfly)

Leucrocuta hebe (Hebe’s flat-headed mayfly)

Maccaffertium mexicanum (southern flat-headed mayfly)

Maccaffertium modestum (modest flat-headed mayfly)

Maccaffertium terminatum (terminal flat-headed mayfly)

Maccaffertium vicarium (march flat-headed mayfly)

Nixe kennedyi (stream mayfly)

Paraleptophlebia debilis (fragile prong-gilled mayfly)

Pentagenia vittigera (common spiny-headed burrowing mayfly)

Siphlonurus alternatus (northern summer mayfly)

Sparbarus maculatus (maculated small square-gilled mayfly)

Stenacron interpunctatum (orange cahill)

Stenonema femoratum (dark cahill)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

giant mayfly

 

 

 

 

 

 

 

 

 

 

pond olive

 

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Created 11/5/2020

Last Updated:

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