City of Salem, Oregon Public Works Water

Macroinvertebrates, commonly called macros, are water “bugs” that are large enough to see with our eyes and have no spines. They are important to stream diversity. Macros come in various types including water mites, aquatic worms, dragonfly nymphs, mayfly nymphs, and more. For this post we will focus on stonefly nymphs. As adults, stoneflies are terrestrial insects that lay their eggs in freshwater. Each female may produce as many as 6,000 eggs that grow into stonefly nymphs that live in a waterbody, such as a stream. Stonefly nymphs have two tails and 6 legs. They feed on plants, organic decaying matter, and other insects. Stoneflies, along with caddisflies and mayflies, are important indicators of stream health. Certain species of these three types of macroinvertebrates are sensitive to pollution; therefore, they indicate good water quality where they are found. Macroinvertebrates are also important food for fish.

Learn more about cool creek critters at…/08-009_01_Macroinvertebrate-Field-Guide….