New, fully illustrated characters provide for definite identification of North American dragonfly nymphs to family, genus and species levels
Once a users make an identification, follow-up diagnostic features are provided so they can verify that they have arrived at a correct identification
Characters used in previous nymph identification keys are evaluated, and errors and misleading couplets are analyzed
Life cycle data and functional morphology of various nymph features important in their survival are provided; almost no information on these aspects of dragonfly nymph biology is found in previous works