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Insect Identification Key
Identify Insects in Michigan ... and beyond!

Cornicles and cerci
Each of the illustrations marked A, B and C show insects that have cornicles, the pair of tubes that extend up and out from the rear of the abdomen. The illustration at right shows an insect that has appendages called cerci. Cerci come in many different shapes and sizes. Illustration sources: Cornicle illustrations are from R.E. Snodgrass, Insects, Their Way and Means of Living., and the cerci illustration is from A.D. Imms’ paper in Transactions of the Linnean Society of London Zoology, 1913.

Your answer to the previous question was that your insect is doesn't have the following combination of characteristics: small in size and with a fuzzy appearance.

Does your insect have cerci or cornicles?

Cornicles and cerci are both extensions that arise from the rear of the abdomen. Cornicles, which are sometimes called siphuncules, look somewhat similar to cerci, but unlike cerci, they secrete droplets of fluid. The droplets harden into what is called “cornicle wax,” which is used to defend the insect against its predators. For examples, see the photos at right.

Click one of the following:

Yes, my insect has cerci or cornicles.

No, my insect does not have either of these characteristics.

I would like to return to the start of this key.

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Unless noted otherwise, photographs on this website are the property of the photographers and may not be reused without written permission from the photographers. To obtain permission, email the photographers here. High-resolution versions of the photographs are available.

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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