What is a Dragonfly?

Dragonflies are insects of the order odonata and closely related to damselflies, which are of the same order of insects. Damselflies tend to be smaller and "daintier" than dragonflies, though there are some small dragonflies as well. Dragonflies always perch with their wings outspread. Damselflies perch with their wings folded together over their backs or partially outspread and angled backward. This website does not delve into damselflies.

Dragonflies are characterized by their amazing eyesight and fantastic flying ability. These two traits along with what amounts to an onboard computing system linking eyesight and complex wing control with an ability to isolate and focus on targets are what ranks them high among the deadliest hunters on the planet. Scientists estimate that lions have successful hunts about 25% of the time, great white sharks approximately 50% of the time, and dragonflies an impressive 95% of the time!*

*Nature's Drone, Pretty and Deadly : NY Times article reporting research on dragonfly predatory prowess

Eyesight

Blue Dasher, Champaign, IL

Dragonfly eyes consist of up to 30,000 facets ("ommatidia"), see about 200 frames per second in contrast to human vision at 60 frames per second and have a reaction time of about 30 milliseconds.* Their eyes have from 15 to 33 color sensitive opsins, compared to 3 opsins in human eyes (red, green and blue for humans).** In addition they can detect polarized light which probably facilitates navigation to water.

*How do Dragonflies See the World? Animal Super Senses : very nice video from BBC presenting the incredible specialization of dragonfly sight
**Extraordinary diversity of visual opsin genes in dragonflies in the Proceedings of the National Academy of Sciences : abstract of the paper with link to the full text available there as well

Flight

Male Common Green Darner in Flight, Middle Fork Forest Preserve N. Waterfowl Area

Dragonflies fly forward, backward, side to side, can turn on a dime and hover.
Dragonflies have direct drive musculature for their wings (rather than indirect, common among other insects).*
They move all four wings independently of each other. This is unique in the insect world. This includes wing shape, stroke length, complete stops and angle of attack.*
Dragonflies have four methods for generating lift. Modern aircraft only two, and one of those only briefly.*
Some species can hit top speeds of 30mph.**
Because their wings beat only about 30 beats per second, they do not make the annoying hum of flies or mosquitoes (mosquitoes beat about 400 beats per second)**

*Tree of Life Dragonfly Flight : a succinct but informative article summarizing a lot of research
**The Secret of the Dragonfly Flight Revealed : a news article reporting on this research but also mentioning a wing rate of 20-30 beats per second.

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