Dragonflies have been around longer than dinosaurs. Except for size, they’ve changed little through time. They’ve gone from a wingspan about the size of an adult shin (between knee and ankle), to palm-sized (stretching between a fully extended thumb and pinky).
Evolutionary biologists believe that size reduction is connected with decreased oxygen levels in the atmosphere.
Dragonflies are fierce hunters, expert flyers, and the subject of artificial intelligence and robot developers.
Recent dragonfly brain studies can now explain the mechanisms behind the aerial acrobatics. Like the human brain, dragonflies have target-detecting neurons that track moving objects and predict where it will go.
Dragonfly Super Skills
- Approximately 80% of the dragonfly brain devoted to the visual processing
- Some species can see prey up to 30 feet away
- Movement detection up to 60 feet away
- Almost 360⁰ range of vision
- Hunt capture rate in the high 90% range
- Seizes prey with feet and eats while flying
Swarm Behavior Studies
Swarm behavior is still not fully understood, but puzzle pieces are falling into place as scientists amass data.
Biologists know there are static (food source) and migratory swarms. The two types may be related.
Generally, both swarm types follow these patterns;
- They occur more in the midwestern states
- Take place before a storm that follows a hot, dry spell
- Happen between July – October with September being the peak
- They follow coastlines and lakeshores
- Dragonfly migrations appear to match bird migration patterns
Life Cycle – Up to 5 Years – Most of it Under Water
Mating – Mid to late summer.
Egg-laying – Females lay eggs in still waters on submerged aquatic plants or in shallow areas. In cooler zones, like Nevada County, dragonfly eggs wait until spring to hatch.
Nymph – Molts up to twelve times and can live for as many as four years in the water.
Nymphs are voracious eaters, happily dining on;
- mosquito larvae
- small fish
- each other
All dragonflies must have clean, fresh water to live.
Adult – The final molt is completed above the water’s surface in late spring or early summer. They live only two to four months before dying.
Adult Dragonfly Diet
Features for Dragonfly Friendly Water Gardens
Dragonflies breed in water. To encourage dragonflies and damselflies, include these features in your pond, trough, or marsh area;
- water free of pesticides & fertilizers
- protected from wind
- well oxygenated
- receives 5-6 hours of the midday sun
- flat rocks near pond edges for sunbathing
- shallow areas (but not so shallow it dries up)
- aquatic vegetation, especially reeds and lilies
- cover for final molting safety
- tall above water plants for perching
Websites devoted to dragonfly symbolism are diverse! The meaning that cultures apply to dragonflies seems to be as diverse as the people who observe them. Below are a few examples.
Change, Transformation & Adaptability – Worldwide
Swiftness, Activity & Purity – Native Americans
Good Luck, Harmony & Prosperity |Instability & Weakness – Chinese
Light & New Joy| Irresponsibility & Unreliability – Japanese
A dragonfly will lead you to fairies – Ireland & Europe
Horse possessed by the devil – Romania
Eye Pokers – Norway
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University of Notre Dame – Massive Swarm Migrations of Dragonflies (Odonata) in Eastern North America
Bay Nature magazine – Why Do Dragonflies Swarm?
California Department of Food and Agriculture – Insecta: Odonata
Dragonfly Swarm Report – Help amass worldwide data on dragonfly swarms
Flickr – Northern California Dragonflies by David A. Hofmann
The Guardian – Discovering Dragonflies that Cross Oceans
Insect Identification for the casual observer
Live Science – Dragonfly Shows Human-Like Power of Concentration
Odanata Central – Nevada County, CA
Pacific Horticulture Society – Garden Allies: Dragonflies and Damselflies
Popular Mechanics – Attract Dragonflies to your Yard for All-Natural Pest Control
ScienceDaily – Dragonfly brains predict the path of their prey
Sciencing – Life Cycle of a Dragonfly
Smithsonian.com – 14 Fun Facts About Dragonflies
UC Berkeley- Odanata
Wikipedia – Maganeura