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Insect Identification Key
Order Psocodea (formerly Psocoptera): the booklice, barklice and barkflies

A barklouse
This barklouse is in the typical posture — holding its membranous wings roof-like over its body. This particular species is Graphopsocus cruciatus. Photo credit: Jean-Jacques MILAN.
Click here to see examples of more booklice, barklice and barkflies!

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

Members of this order include: booklice, barklice and barkflies (among others).

Etymology: Psocodea comes from the Greek word psocos, which means gnawed, and refers to the insects&rsquol; use of gnawing when eating.

General characteristics of booklice and barklice:
• small
• soft-bodied
• two pairs of membranous wings (some are wingless)
forewings not heavily veined
• rear wings are smaller than forewings
• at rest, wings are held roof-like over the body
• large head that connects to the thorax via a short and thin “neck”
hemimetabolous metamorphosis (egg — nymph — adult)

Click here to see examples of more booklice, barklice and barkflies!

Number of species worldwide: about 4,500

Basic ecology:
As you might expect, booklice are often found in books, where they actually feed on the binding. In addition, booklice will eat flour and other grains, as well as other starchy items, including wallpaper paste. Barklice are typically found outdoors, often under bark or leaf litter. Barklice feed on fungi, lichen and plants.

Kingdom Animalia
   Phylum Arthropoda
      Class Insecta
         Order Psocodea (formerly Psocoptera)

Classification note: The barklice, booklice and barkflies were once described in their own order, called Psocoptera, but have now been combined with the former orders Mallophaga and Anoplura, and all now fall within the newly named order Psocodea.

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

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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