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Insect Identification Key
Order Psocodea (formerly Mallophaga/Phthiraptera): the chewing lice

Anoplura and Mallophaga
The order Psocodea (formerly Phthiraptera) includes sucking lice and chewing lice. The two can be distinguished by the size of the head. If the head is narrower than the thorax, it is one of the sucking lice. If the head is broader than the thorax, is is one of the chewing lice. Illustration credit: Centers for Disease Control.

Based on your answers to the questions, you have identified your insect as being in the order Psocodea (formerly Mallophaga/Phthiraptera): the chewing lice!

Members of this suborder include: chewing lice, including bird lice and biting lice.

General characteristics:
• small (10 mm or smaller)
• wingless
dorsoventrally flattened
chewing mouthparts
• small compound eyes, absent altogether in some species
• no ocelli
• antennae, if visible, with three to five segments
• hard larger than the thorax
forelegs held up near the head
hemimetabolous metamorphosis (egg — nymph — adult)

Number of species worldwide: about 3,500

These chewing lice are parasitic on animals. They are ectoparasites, meaning that they feed at the surface of the host animal. (An endoparasite lives inside the host's body. An example of an endoparasite is a tapeworm.) In this case, the chewing lice eat such things as feathers, hair, scales and dried blood.


Kingdom Animalia
   Phylum Arthropoda
      Class Insecta
         Order Phthiraptera
            Suborder Mallophaga
            Suborder Anoplura

Classification note: Mallophaga was once described as its own order and as a suborder with the order Phthiraptera. Today, Mallophaga is combined with the former orders Anoplura and Psocoptera, and fall under the 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 correct identification 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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