Macroinvertebrate Identification Key
Macroinvertebrates are animals without a backbone that can be seen with the naked eye. These bottom-dwelling animals include crustaceans and worms but most are aquatic insects. Beetles, caddisflies, stoneflies, mayflies, hellgrammites, dragonflies, true flies, and some moths are among the groups of insects represented in streams. Macroinvertebrates are an important link in the food web between the producers (leaves, algae) and higher consumers such as fish.
Can you tell the difference between a damselfly and a mayfly?
We can help. If you want to identify an aquatic macroinvertebrate you found in a stream, scroll down to use our macroinvertebrate identification key.
Using the online key
The macroinvertebrate identification key is an example of a dichotomous key. At each step you choose between two mutually exclusive statements about a characteristic.
This key starts with the choice between “jointed legs” and “no jointed legs”. After you make that choice you move to the next pair of choices in the key. Follow the page reference (e.g. “Go to Page 3”) to jump to the next part of key. Continue until you arrive at an identification.