Stonefly, order Plecoptera, nymph on underside of rock from a stream

Stonefly, order Plecoptera, nymph on underside of rock from a stream

MShieldsPhotos / Alamy Stock Photo

Image ID: AD34R1

Stoneflies live underneath rocks in flowing streams with good water quality. Their presence is used, along with other macroinvertebrates that require high dissolved oxygen, as an indicator of a stream's health. When they molt it is known as a hatch, and trout feed on the flies.