Common green darner

Anax junius

One of nature’s unheralded migrations is that of the green darner. If you watch carefully along a shoreline where dragonflies congregate in late summer, you may notice that the seemingly random wanderings of these insects is, in fact, a concerted movement.

On very rare occasions, the movement becomes a tidal wave, or “storm,” of insects rushing by. Clouds of more than 1 million southbound dragonflies have been observed in the eastern U.S., a mere trifle next to the record swarm of 4 billion to 6 billion spotted in South America.

The migration phenomenon has scarcely been documented, but biologists believe that green darners, after arriving in the tropics each fall, lay eggs of offspring that will return north as adults in the spring. The green darner is one of the biggest and fastest dragonflies, its speed aided by a wide wingspan.

Natural History

Green darners occur throughout California around slow-moving and still waters, where males patrol aggressively for rivals or potential mates. During migration, they can be found nearly anywhere but tend to follow lines in the landscape such as roads, rivers or ridgelines. When in hordes, they look like a wave flowing over the land.

Key Characteristics

Large and handsome, with a stocky green thorax, sky-blue abdomen and a yellow face. The most common and widespread dragonfly in North America.