Conservation Status

Four species of stoneflies are listed by the World Conservation Union (IUCN). One is listed as Extinct, or no longer liv

HOW CLEAN IS YOUR STREAM?

Aquatic insects are used to measure the quality of freshwater habitats. One method of measuring water quality is to count the total number of larvae of three pollutionsensitive insect groups: mayflies, stoneflies, and caddisflies. This number is compared with the total number of pollution-tolerant fly larvae known as midges. Streams with more mayflies, stoneflies, and caddisflies and fewer midges are less likely to be polluted than other streams in the same area with relatively more midges.

ing; two are listed as Vulnerable, or facing a high risk of extinction in the wild. The fourth species lacks sufficient information to determine the chances of it becoming extinct. Habitat destruction caused by development, logging, and other man-made or natural events that change water quality are the greatest threat to stonefly populations.

Stonefly species are sometimes found only in a particular stream system or are considered rare and restricted to a small geographic region. This has resulted in the development of local, regional, and state lists that identify these species and their need for special consideration and further study. Stonefly larvae have similar space and clean water requirements to small trout and other fish of similar size. Techniques used to maintain healthy native fish populations might work equally well to manage populations of stonefly larvae. However, these practices are rarely used to protect stonefly habitats.

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