Mayflies (Ephemeroptera), caddisflies (Trichoptera), and stoneflies (Plecoptera) are the most common insects in these undisturbed streams.
Large populations of species in the insect orders Ephemeroptera, Plecoptera and Trichoptera.
Thus, like a canary in a coal mine, researchers can examine stream hydropsychid populations to assess stream health (see EPT or Index of biological integrity).
Biological monitoring metrics have been developed in many places, and one widely used measure is the presence and abundance of members of the insect orders Ephemeroptera, Plecoptera and Trichoptera.