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Insect Identification Key
Order Trichoptera: the caddisflies

A caddisfly
This is a caddisfly. Notice its long antennae and rather moth-like appearance. The hairs that cover its wings and body are not evident in this photo, but they are present. Photo credit: Leslie Mertz. Photographed in Luce County, Michigan, USA on May 27, 2012.

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

Members of this order include: the caddisflies, which sometimes go by the name of sedgeflies, railflies or millers.

Etymology: Trichoptera comes from the Greek words trichos, which means hair, and ptera, which means wings. This refers to the hair-covered wings present in these insects.

General characteristics:
• hair-like antennae that are about as long as the body or longer (some species have antennae that are much longer than the body)
• two pairs of wings that are narrower close to the body, and widen as they extend outward
• tiny, silky hairs covering the wings and the body
• wings that are held roof-like over the back (highest above the center of the back, and then sloping downward and outward)
• large compound eyes
forewings slightly longer than hind wings
• in some species, the hind wings are broader than the forewings
• paired spurs on each tibia
holometabolous metamorphosis (egg — larvapupa — adult)

Basic ecology:
Caddisflies usually live around rivers, streams, lakes, ponds and other bodies of freshwater, including vernal pools (temporary pools of water, often seen in the spring). In fact, although the adults are terrestrial, their larvae are aquatic. The larvae are quite interesting: Many of them build tubular cases of out of silk and studded with small pebbles and sand, twigs, and other bits of material from their surroundings. You may have noticed these small tubes stuck to rocks you’ve picked up from a riverbed. If you’re patient, you might see a larva poke outside of the tube.

Number of species worldwide: about 12,000

Kingdom Animalia
   Phylum Arthropoda
      Class Insecta
         Order Trichoptera

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

Classification note:

Note: Even though their names may sound like it, caddisflies 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!

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

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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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