What type of insect is most often used for studying water quality due to their sensitivity to pollution?

Mayflies are often used for studying water quality because they are highly sensitive to changes in their aquatic environment, particularly pollution. Their presence or absence in a body of water can indicate the health of that ecosystem. Mayflies are part of a larger group known as bioindicators, which are organisms used to assess the biological integrity of an environment. Their life cycle includes a nymph stage that lives in water for several months to years, during which they are vulnerable to pollutants. The decline in mayfly populations can signal deteriorating water quality, making them an effective tool for monitoring aquatic ecosystems and understanding the impacts of human activities on freshwater habitats.

In contrast, much of the other insect groups listed, like beetles, moths, and butterflies, do not inhabit aquatic environments in their early life stages or are less sensitive to water quality changes, making them less effective for this specific type of environmental assessment.