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Posts tagged “Anax junius

Common Green Darners Migrating South

Monarchs aren’t the only insect that are seasonal migrants.  The Common Green Darner dragonfly and a few other dragonfly species are as well.  However, where Monarchs move northward in the spring over several generations, one generation of Common Green Darners flies all the way from southern U.S., Mexico and the Caribbean in the spring to New England and Canada.  Here they lay eggs which give rise to a second generation that migrates south in September and October. Upon reaching their destination they then breed. A third generation emerges around November and lives entirely in the south during winter.  It’s their offspring that start the cycle again by swarming northward as temperatures warm in the spring.

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Common Green Darners Mating & Laying Eggs

Darners are a family of dragonflies whose members are quite large (some over three inches in length).  Common Green Darners (Anax junius) are one of only two darners in the Northeast with an entirely green thorax (section between head and abdomen).  Often you find them perching low in grasses and weeds.  Males tend to fly along the shorelines of ponds, patrolling for females and keeping other males at bay. 

After mating takes place, the males of some species of dragonflies disappear.  In other species, the male stays nearby, guarding the female and fending off other males that might remove the initial suitor’s sperm and replace it with their own.  Some species go to the extreme of remaining attached to each other while egg-laying takes place.  Common Green Darners are the only species of darner that often lays in this manner – in tandem, with the male still clasping the female while she submerges her abdomen and lays her eggs in aquatic vegetation (pictured).

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Common Green Darners Appearing

6-20-17 common green darner 021The Common Green Darner (Anax junius) is one of our most common dragonflies. often seen near ponds. The family of dragonflies known as “darners” consists of species with large eyes and long abdomens that tend to rest infrequently and when they do rest, usually hang vertically. The Common Green Darner is the only North American darner in which the male and female usually fly in tandem when the female is laying her eggs on emergent vegetation.

Up to 50 of the world’s 5,200 dragonfly species migrate and the Common Green Darner is one of them. In the fall most (but not all) adult Common Green Darners migrate south to Florida, eastern Mexico and the West Indies. Huge clouds of migrating dragonflies have been seen along the East Coast, Gulf Coast and the Great lakes in autumn. Transmitters weighing 1/100th of an ounce that have been attached to migrating dragonflies confirm that they migrate much like birds. Just like avian migrators, they build up their fat reserves prior to migrating; they follow the same flyway as birds, along the Atlantic Coast; and like birds, dragonflies don’t fly every day but stop and rest every three days or so.

Some dragonflies mate and lay eggs along the way, while others do so when they reach their destination. The eggs hatch, larvae develop and the adults head north in the spring. Unlike birds, migration is only one-way for dragonflies. It is the offspring of the fall migrating generation that migrate north in the spring. Here in the Northeast, most arrive before any resident Common Green Darners have emerged. (photo:  female Common Green Darner)

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Common Green Darners Migrating

9-16-13 common green darner 249The Common Green Darner, Anax junius, is one of our largest dragonflies, measuring three inches long, with a four-inch wingspread. It is strikingly colored, with a green thorax and a bright blue (male) or reddish (female) abdomen. As if that weren’t enough to set this dragonfly apart, it is also migratory. Common Green Darners migrate south from August to November, stopping over (like migrating birds) occasionally along the way, resuming flight after resting and refueling. Thanks to radio telemetry, we now know that over a two-month migration, Common Green Darners, each weighing about one gram, can migrate over 400 miles. (Photograph is of a Common Green Darner perched on Bottle Gentian.)

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