Which insect is used as 'Ecological indicator'?

Solution(By Examveda Team)

Plecoptera insect is used as 'Ecological indicator'.
Most insects like beetles, ants, honeybees, and butterflies are used as biological indicators in this study because they are sensitive to even a slight change in the environment and are also used in monitoring various pollutants in environment.
All species of Plecoptera are intolerant of water pollution, and their presence in a stream or still water is usually an indicator of good or excellent water quality.
Due to their nymph's requirement for well-oxygenated water, the species is very sensitive to water pollution. This makes them important indicators for water quality.