• Posterior spiracles present on slits on both sides of either, a vertically linear stigmatal bar, or a retractable laterally compressed spine
• Body integument with longitudinal striations, except when covered by pubescence
• First seven abdominal segments have no projections other than, 3-4 pairs of fleshy pseudopodia (setae-bearing swellings) or prolegs

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