Several slowly evolving characters are evaluated with the main objective of reinforcing the higher classification of Embioptera. An embiopteran femoral auditory organ, described here for the first time, exhibits differences in shape and position that provide diagnostic criteria for higher taxonomic groups in the order. New characters on silk ejectors, bladders, and various types of leg setae are also discussed within a taxonomic framework. The utility of these new traits and their different conditions, for identifying monophyletic groups, was tested by a preliminary phylogenetic analysis.