• Legs absent
• Labrum not represented as separate sclerite
• Thorax and abdomen cylindrical, flattened, or fusiform
• Abdominal tergites without dorsal lobe, antennae with three segments or more
• Abdomen with 10 segments
• Mandibles falcate (sickle-shaped), without molar lobe various marginal habitats

Merritt, R W., K W. Cummins, and M B. Berg. An Introduction to the Aquatic Insects of North America. Dubuque, Iowa: Kendall/Hunt Company, 2008