Many details, although clearly visible at close range, cannot be seen at a distance, and they must be noted to proceed through the key. Once the species are learned in the hand, many of them will be easily recognizable in the field. Each number in the key contains a pair of statements, each of which describes distinguishing characteristics. Read each statement before deciding to accept or reject either one, and note that some of them list more than one characteristic. Each one will lead either to a species name or another number.
Measurements listed refer to total length unless otherwise indicated.
When two are more species are listed together, they are difficult to distinguish in the field but differ by structural characteristics that are explained and illustrated in more technical books such as The Dragonflies of British Columbia , by Robert Cannings and Kathleen Stuart, or The Odonata of Canada and Alaska , by Edmund Walker. Males and females can be distinguished as follows. An important feature for identification in some families is the vulvar lamina under the 9th abdominal segment that supports the eggs about to be laid. The definitive coloration of adults is acquired slowly with maturation, and individuals that are not yet mature may not be fully colored. Male dragonflies on territory at the water or individuals of either sex engaged in reproductive behavior will surely be mature.