What Is Odonata? Dragonflies and Damselflies Explained

Updated

Odonata is the insect order that contains dragonflies and damselflies. If you want to tell the two apart, look at body build, wing position at rest, eye spacing, and flight style. DragonflyPix, a site selling photographs of European and Australian dragonflies and damselflies, is a useful place to see both groups and to learn how a photo's caption records species, place, and camera settings.

The two suborders: Anisoptera and Zygoptera

Odonata splits into two well-known groups:

  • Anisoptera — dragonflies. The name refers to unequal wing pairs, though the visible difference is mainly in build and behaviour.
  • Zygoptera — damselflies. The name refers to equal wing pairs.

DragonflyPix uses the same split in its site keywords and in its photo IDs: IDs beginning with "Dr" are dragonflies and "Da" are damselflies. As of June 2021, the site's IDs ran from Da001 to Da940 and Dr0001 to Dr1740, which gives a rough sense of how many photos of each group it holds.

How to tell a dragonfly from a damselfly

Use these four checks together rather than relying on one:

Feature Dragonflies (Anisoptera) Damselflies (Zygoptera)
Body Stouter, heavier build Slender, needle-like body
Wings at rest Held open, roughly horizontal Usually folded together above the back
Eyes Large eyes that meet or nearly meet on top of the head Eyes set apart on the sides of the head
Flight Strong, fast, often patrolling or hovering Weaker, more fluttering, often low among vegetation

These are general rules, not absolutes. Some damselflies hold their wings partly open, and some dragonflies perch with wings angled forward. When a single feature is ambiguous, check the eyes and body shape next.

Reading a DragonflyPix photo caption

On DragonflyPix, clicking a thumbnail opens the photo in a new window with 13 pieces of information underneath. The site gives this example from the Azure Bluet (Coenagrion puella) species page:

1 / 20; PhotoID: Da071 21/06/2016 15:32 Sweden F8 1/160 180mm ISO400 Canon7D2 -Crop -Flash MF

What each part means:

  • 1 / 20 — this is the first of 20 photos of that species on the site.
  • PhotoID: Da071 — the unique photo identifier; "Da" marks a damselfly, "Dr" a dragonfly.
  • 21/06/2016 15:32 — date and time the photo was taken.
  • Sweden — country of the sighting.
  • F8, 1/160, 180mm, ISO400 — aperture, shutter speed, focal length, and ISO.
  • Canon7D2 — camera model.
  • -Crop — the photo was not cropped; cropped photos would show "+Crop" (as of January 2023 the site had none).
  • -Flash — no flash was used.
  • MF — manual focus.

This format is worth copying in your own field notes: species, date and time, location, and camera settings make a sighting verifiable and comparable with other records.

Using the site's images

DragonflyPix states that its thumbnails and small versions (1200 x 800 pixels) may be downloaded freely, but they must not be distributed to third parties, modified, or published on another website or by other means without prior written permission. The same restriction applies to the site's text. If you plan to use an image in a presentation, blog, or publication, request permission first.

Practical next step

If you are new to the order, start with a species page for a common damselfly such as the Azure Bluet, read its caption fields, then compare it with a dragonfly page. Checking the eyes, resting wing position, and body shape against the photo will quickly make the Anisoptera–Zygoptera distinction automatic.