Plecoptera is an order of insects commonly known as stoneflies. They are primarily found in clean, cold freshwater environments, such as rivers and streams. Stoneflies have a distinct life cycle that includes an aquatic nymph stage, where they live underwater for several months to years before emerging as adults. Adult stoneflies are characterized by their two pairs of membranous wings and long antennae. They are typically found near water sources and are known for their sensitivity to pollution, making them important indicators of environmental health. Stoneflies play a crucial role in aquatic ecosystems, serving as food for fish and other wildlife.