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Insect Identification Key
Order Ephemeroptera: the mayflies

Mayfly swarm
Mayflies often hatch in large numbers, creating huge swarms. This photo shows a typical scene around the water during a massive mayfly hatch. Photo credit: Photo by Eric Cummings, USGS, UMESC, 2007.
Click here to see examples of more mayflies!

Based on your answers to the questions, you have identified your insect as being in the order Ephemeroptera!

Members of this order include: mayflies (sometimes called fishflies).

Etymology: Ephemeroptera comes from the Greek ephemera, which means ephemeral or short-lived, and ptera, which means wings. Ephemeroptera, therefore, means a winged insect with a short life, which is a reference to the fact that the typical adult mayfly lives only a day or so. See an adult mayfly by clicking here.

General characteristics:
• two pairs of net-veined, somewhat triangular-shaped wings
• the front pair of wings is much larger than the hind pair (some species lack hind wings altogether)
• two long threadlike cerci, usually with a third, similarly long and thin caudal filament between them
• soft body
• large eyes that typically cover most of the head
• wings are held vertically when the insect is at rest
• two short, bristly antennae
• long and thin abdomen
hemimetabolous metamorphosis (egg — naiad — adult)

Click here to see examples of more mayflies!

Number of species worldwide: about 2,000

Kingdom Animalia
   Phylum Arthropoda
      Class Insecta
         Order Ephemeroptera

For a list of all of the orders in this key, click here: List of Orders.

Classification note: Fishflies and mayflies are not flies. True flies are in the order Diptera.

Oops! If this doesn't appear to be the order for your insect, go back through the key and look more carefully at your insect while answering the questions again. Your perseverance will reward you!

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Photos at the top of this website are (from left to right): potato beetle (Leptinotarsa decemlineata) — photo credit: Scott Bauer, U.S. Department of Agriculture; ebony jewelwing (Calopteryx maculata)— photo credit: U.S. Fish and Wildlife Service; sweat bee (Agapostemon splendens) — photo credit: Natalie Allen and Stephanie Kolski, U.S. Geological Survey; preying mantis, monarch butterfly (Danaus plexippus), hellgrammite (aka toe biter) larva and eyed click beetle (Alaus oculatus) — photo credit: Leslie Mertz; Halloween pennant (Celithemis eponina) — photo credit: Kay Meng, U.S. Fish and Wildlife Service.

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