Darners, Family Aeshnidae

Habits and Traits of Darners, Family Aeshnidae

Common green darner.
Common green darner. Flickr user Bob Danley (CC by SA license)

Darners (Family Aeshnidae) are large, robust dragonflies and strong fliers. They're usually the first odonates you'll notice zipping around a pond. The family name, Aeshnidae, was likely derived from the Greek word aeschna, meaning ugly.

Description

Darners command attention as they hover and fly around ponds and rivers. The largest species can reach 116 mm in length (4.5 inches), but most measure between 65 and 85 mm long (3 inches).

Typically, a darner dragonfly has a thick thorax and a long abdomen, and the abdomen is slightly narrower just behind the thorax.

Darners have huge eyes that meet broadly on the dorsal surface of the head, and this is one of the key characteristics to differentiate members of the family Aeshnidae from other dragonfly groups. Also, in darners, all four wings have a triangle-shaped section that extends lengthwise along the wing axis (see an illustration here).

Classification

Kingdom – Animalia

Phylum – Arthropoda

Class – Insecta

Order – Odonata

Suborder - Anisoptera

Family - Aeshnidae

Diet

Adult darners prey on other insects, including butterflies, bees, and beetles, and will fly considerable distances in pursuit of prey. Darners can catch small insects with their mouths while in flight. For larger prey, they form a basket with their legs and snatch the insect out of the air. The darner may then retreat to a perch to consume the meal.

Darner naiads are also predaceous and are quite skilled at sneaking up on prey. The dragonfly naiad will hide within the aquatic vegetation, slowly crawling closer and closer to another insect, a tadpole, or a small fish, until it can strike quickly and catch it.

Life Cycle

Like all dragonflies and damselflies, darners undergo simple or incomplete metamorphosis with three life stages: egg, nymph (also called larva), and adult.

Female darners cut a slit into an aquatic plant stem and insert their eggs (which is where they get the common name darners). When the young emerges from the egg, it makes its way down the stem into the water. The naiad molts and grows over time, and may take several years to reach maturity depending on the climate and species. It will emerge from the water and molt a final time into adulthood.

Special Behaviors and Defenses:

Darners have a sophisticated nervous system, which enables them to visually track and then intercept prey in flight. They fly almost constantly in pursuit of prey, and males will patrol back and forth across their territories in search of females.

Darners are also better adapted to handle cool temperatures than other dragonflies. Their range extends farther north than many of their odonate cousins for this reason, and darners often fly later in the season when cool temperatures prevent other dragonflies from doing so.

Range and Distribution

Darners are widely distributed throughout the world, and the family Aeshnidae includes over 440 described species. Just 41 species inhabit North America.

Sources

  • Aeshna vs. Aeschna. Opinions and declarations rendered by the International Commission on Zoological Nomenclature (1958). Vol. 1B, pages 79-81.