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Insect Identification Key
Aphids of the Superfamily Aphidoidea, which in in the Suborder Sternorrhyncha of the Order Hemiptera

Green apple aphid (Aphis pomi)
These are the different life stages of the green apple aphid (Aphis pomi): adult female (A); adult male (B); female nymph (C); adult female laying an egg (D), and eggs, which are laid green, but become black (E). Illustration credit: USDA/R.E. Snodgrass, Insects, Their Way and Means of Living, plate 2..Click here to see examples of more aphids!

Based on your answers to the questions, you have identified your insect as being an aphid, which is in the suborder Sternorrhyncha!

General characteristics:

In overall appearance, some aphids can be easily identified as insects, while others may look little like actual insects. The photos at right show the two variations.

Even though aphids may look very different from one another, all aphids do share one feature: cornicles, which are small tubes that extend from the end of the abdomen. When aphids are disturbed, they secrete fluid from the cornicles. This fluid hardens into what is called cornicle wax. This substance is distasteful to many of an aphid’s predators, so it serves a protective function.

Besides cornicle wax, aphids also secrete another fluid called honeydew. This fluid is actually the aphid’s waste product. Since aphids typically feed on plant sap, which contains sugar, their waste products are sweet.

Many insects snack on honeydew. In fact, some ants will act as shepherds for a group of aphids. The ants will tend the “flock,” protecting the aphids from predators, while gathering the honeydew droplets the aphids produce.

To learn about the suborder Sternorrhyncha, of which aphids are a part, click here.


Kingdom Animalia
   Phylum Arthropoda
      Subphylum Hexapoda
         Class Insecta
            Order Hemiptera
               Suborder Sternorrhyncha
                  Superfamily Aphidoidea

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 of 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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