Aquatic entomology is the study of insects that live in the water during all or part of their lives. Many flying insects such as dragonflies, damselflies, caddisflies spend their larval youth in a stream, where they are the primary prey of fish. You can tell a lot about the quality of the water in a stream by the species living in it. Aquatic Entomologists sample, count, and identify the BMIs in a stream. Most BMIs thrive in clean water; relatively few tolerate ...