Excerpt: The identification of organisms is a prerequisite to developing water quality criteria for aquatic life. Identification is necessary because differences in water quality requirements are specific and may be different for closely allied species. The taxonomy of various species, particularly those associated with the aquatic environment, is much more detailed and better known for adults than for immature instars. To facilitate correlation of adult and larval forms, a trap was needed to collect the emerging adults from the various streams.
Lemke, Armond E. and Mattson, Vincent R.
"An Emergence Trap for Aquatic Insects,"
The Great Lakes Entomologist, vol 2
Available at: https://scholar.valpo.edu/tgle/vol2/iss1/4