Macroinvertebrates The groups of animals found in leaf packs are collectively called benthic macroinvertebrates or "macros" for short. Benthic refers to the bottom, in this case the bottom of a stream. 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. Macros are an important link in the food web between the producers (leaves, algae) and higher consumers such as fish. Common Stream Macroinvertebrates All insects go through a series of changes (metamorphoses) during their life cycle. Insect life cycles can be grouped as either complete or incomplete metamorphoses. A complete metamorphosis includes a pupae stage. The adult and larva tend to look very different from each other. Incomplete metamorphosis lacks the pupae stage and the nymph and adult are more similar in appearance. Most aquatic insects remain underwater in the immature stages and leave the stream only as adults. The life cycles of macros can range from a few weeks to several years. Incomplete Metamorphosis Complete Metamorphosis (Egg – nymph - adult) Mayflies Stoneflies Dragonflies/Damselflies True bugs (Egg - larva - pupa - adult) Caddisflies Dobsonflies/alderflies Beetles True flies Aquatic moths To see images of macroinvertebrates, visit New York State Department of Environmental Conservation's Key to Aquatic Macroinvertebrates.