giant mayfly

(Hexagenia limbata)

Conservation Status
giant mayfly
Photo by Luciearl
  IUCN Red List

not listed

     
  NatureServe

N5 - Secure

SNR - Unranked

     
  Minnesota

not listed

     
           
           
           
           
           
           
 
Description
 
 

Giant mayfly is a large common burrower mayfly. It is very widespread, occuring 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 it 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 (subimagos) 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.

The adult is soft-bodied and, as the common name suggests, large, 516 to 1116 (8.3 to 27.3 mm) in length. It may be the largest mayfly in the United States. The female tends to be larger than the male and has smaller eyes. Color and markings are highly variable. It may be may be yellow, yellowish-brown, brown, or even white.

The antennae are short, bristle-like, and inconspicuous. The mouth parts are small, poorly developed, and non-functional.

There are two hair-like, very long, sensory appendages (cerci) at the tip of the abdomen. The cerci may be as long as the body.

On the hind leg the last part of the leg (tarsus), corresponding to the foot, has 4 segments.

The forewings are clear, large, triangular, and have many veins. They are held together above the body when at rest. There are five cross veins at the tip of each wing. The second terminal branch of the front (anterior) branch of the first fork of the media vein is designated as the M2 vein. The M2 extends downward at the base toward the first cubitus vein Cu1 then bends abruptly upward and continues straight to the outer margin. The hindwings are much smaller than the forewings. The R4+5 vein on the hindwing is not forked.

 
     
 

Size

 
 

Total length: 516 to 1116 (8.3 to 27.3 mm)

 
     
 

Similar Species

 
     
     
 
Habitat
 
 

Larvae are found in organic, silty or mucky bottoms of lakes, ponds, and rivers. 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.

 
     
 
Biology
 
 

Season

 
 

One generation per year, peaking in August.

 
     
 

Behavior

 
 

 

 
     
 

Life Cycle

 
 

The female lays eggs on the water surface. Each egg sinks to the bottom where it overwinters. The nymph hatches in the spring. It creates a U-shaped tunnel in the sediment where it spends most of its life. It lives in the water from 6 months to 3 years, undergoing up to 30 molts. Eventually, it swims to the water surface while at the same time breaking through the larval skin. This subadult stage has functional wings and is called a subimago. It flies to nearby vegetation and molts one last time, emerging as an adult. 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.

 
     
 

Larva Food

 
 

Organic material suspended in the water.

 
     
 

Adult Food

 
 

Adults do not feed

 
     
 
Distribution
 
 

Distribution Map

 

Sources

24, 29, 30.

 
  6/25/2021      
         
 

Occurrence

 
 

Common

Giant mayfly is one of the most widespread mayflies in North America and the most common mayfly in the Midwest. Local populations can be enormous.

 
         
 
Taxonomy
 
 

Order

Ephemeroptera (mayflies)  
 

Suborder

Furcatergalia  
 

Superfamily

Ephemeroidea  
 

Family

Ephemeridae (common burrower mayflies)  
 

Genus

Hexagenia (giant mayflies)  
       
 

Synonyms

 
 

Ephemera limbata

Hexagenia affiliata

Hexagenia angulata

Hexagenia californica

Hexagenia carolina

Hexagenia elegans

Hexagenia kanuga

Hexagenia limbata californica

Hexagenia limbata limbata

Hexagenia limbata occulta

Hexagenia limbata venusta

Hexagenia limbata viridescens

Hexagenia marilandica

Hexagenia mingo

Hexagenia munda

Hexagenia munda affiliata

Hexagenia munda elegans

Hexagenia munda marilandica

Hexagenia munda munda

Hexagenia occulta

Hexagenia pallens

Hexagenia rosacea

Hexagenia variabilis

Hexagenia venusta

Hexagenia viridescens

Hexagenia weewa

Palingenia limbata

Palingenia occulta

Palingenia viridescens

 
       
 

Common Names

 
 

giant mayfly

Michigan hex burrowing mayfly

sandfly

 
       

 

 

 

 

 

 

 

 

Glossary

Cercus

One of a pair of small sensory appendages at the end of the abdomen of many insects and other arthropods. In Odonata, one of the upper pair of claspers. Plural: cerci.

 

Tarsus

On insects, the last two to five subdivisions of the leg, attached to the tibia; the foot. On spiders, the last segment of the leg. Plural: tarsi.

 

 

 

 

 

 
 
Visitor Photos
 
           
 

Share your photo of this insect.

 
  This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Attach one or more photos and, if you like, a caption.
 
 

Luciearl

 
    giant mayfly      
           
 
MinnesotaSeasons.com Photos
 
 

 

 
           
           

 

Camera

     
 
Slideshows
 
Hexagenia limbata
Matthew Woodbridge
  Hexagenia limbata  
 
About

Xxxxxxxxxxxx

 
     

 

slideshow

       
 
Visitor Videos
 
       
 

Share your video of this insect.

 
  This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Attach a video, a YouTube link, or a cloud storage link.
 
 

 

 
     
     
       
       
 
Other Videos
 
  Largest USA Mayfly Metamorphosis Dun to Spinner (Hexagenia Limbata)
Lively Legz/Living4theoutdoors
 
   
 
About

Jul 23, 2014

Watch as a hex mayfly cracks out of it's dun stage and turns into a spinner right in front of my camera.

 
  Hexagenia Limbata (Hex) Mayfly Hatch
TroutnutDotCom
 
   
 
About

Apr 5, 2011

A swarm of Hex mayfly spinners over a river in northern Wisconsin.

 
  Burrowing Mayfly (Ephemeridae: Hexagenia limbata) Female Subimago
Carl Barrentine
 
   
 
About

Aug 7, 2011

Photographed in Wisconsin, across the Mississippi River just North of Red Wing, Minnesota (04 August 2011). Thank you to Roger Rohrbeck (@Bugguide.net) for identifying this specimen!

 
       

 

Camcorder

 
 
Visitor Sightings
 
           
 

Report a sighting of this insect.

 
  This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Be sure to include a location.
 
  Luciearl
7/1/2017

Location: Lake Shore, Mn

giant mayfly

 
           
 
MinnesotaSeasons.com Sightings
 
 

 

 

 

 

Binoculars


Created: 6/25/2021

Last Updated:

About Us | Privacy Policy | Contact Us | © 2021 MinnesotaSeasons.com. All rights reserved.