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Insect Identification Key
Order Plecoptera: the stoneflies

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

This adult stonefly has a long body with long and membranous wings that fold on top of one another when the insect is at rest. This specimen is a Meltwater Stonefly (Lednia tumana). Photo by Jonathan Giersch, USGS.
Click here to see examples of more stoneflies!

Members of this order include: stoneflies.

Etymology: Plecoptera comes from the Greek words pleco, which means folded, and ptera, which means wings. This refers to the hind wings, which lie folded and concealed beneath the front wings when the insect is not flying.

General characteristics:
• long, somewhat dorsoventrally flattened body
• long, multi-segmented antennae
• two long, multi-segmented cerci
• two pairs of membranous wings
forewings are long and narrow and fold atop one another when the insect is at rest, concealing the hind wings
• hind wings are slightly shorter, but considerably wider than the forewings
• the hind wing’s anal lobe (see illustration) is pleated, which allows it to fold beneath the forewings
crossveins form two rows of “windowpanes” in the middle of each forewing
hemimetabolous metamorphosis (egg — naiad — adult)

Number of recognized species worldwide: 1,500-3,000

Kingdom Animalia
   Phylum Arthropoda
      Class Insecta
         Order Plecoptera

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

Classification note: Even though their common names may sound like it, stoneflies are not types of 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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