Answer the questions below.
Are the spines on the 2nd joint of the legs twice as long as the spaces between the spines? Then your damselfly is a Dancer belonging to the genus Argia. See Dancers
Are the spines on the 2nd joint of the legs shorter than the spaces between the spines? Is the last abdominal segment split to form a fork-like tail with blue on segments before it? Then your damselfly is probably a Forktail belonging to the genus Ischnura. See Forktails
Is the last abdominal segment is not split to form a fork-like tail? Then your damselflly is probably a Bluet belonging to the genera Enallagma or Coenagrion, or a Sprite belonging to the genus Nehalennia. See Bluets

Written by Mark Lung and Stefan Sommer, 2000
Illustrations by and Ean Harker, 2002.