Dragonflies and damselflies both belong to the order Odonata. All odonates share certain characteristics, including membranous wings, large eyes, slender bodies, and small antennae. Conversely, there are clear differences between dragonflies and damselfies, outlined in the table below.
Knowing whether the odonate you've observed is a dragonfly or a damselfly will aid you in identifying the insect. For most people, learning the most obvious differences – eyes, body, wings, and resting position – will be sufficient. More serious students of the odonates will want to examine the subtle differences in wing cells and abdominal appendages.
Taxonomists divide the Odonata into three suborders: Zygoptera, the damselflies; Anisoptera, the dragonflies; and Anisozygoptera, a group somewhere in between the two. The Anisozygoptera suborder includes only one or two living odonates, and is not covered in this article.
Source: Dragonflies of the World, by Jill Silsby
Differences Between Dragonflies and Damselflies
|Eyes||most have eyes that touch, or nearly touch, at the top of the head||eyes are clearly separated, usually appearing to each side of the head|
|Body||usually stocky||usually long and slender|
|Wing Shape||dissimilar wing pairs, with hind wings broader at the base||all wings similar in shape|
|Position at Rest||wings held open, horizontally or downwards||wings held closed, usually over abdomen|
|Discal Cell||divided into triangles||undivided, quadrilateral|
|Male Appendages||pair of superior anal appendages, single inferior appendage||two pairs of anal appendages|
|Female Appendages||most have vestigial ovipositors||functional ovipositors|
|Larvae||breathe through rectal tracheal gills; stocky bodies||breathe through caudal gills; slender bodies|