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Posts tagged “Aeshnidae

“Mating Wheels”

Dragonflies and damselflies both create what are called “mating wheels” when they mate.  The male grasps the female at the back of her head with the terminal appendages at the end of his abdomen and the female curls her abdomen forward until the tip of her abdomen reaches the male’s sex organs.

Many male dragonflies go to great lengths to make sure their sperm have reproductive success. Prior to mating they often remove any sperm that happen to be in the female from previous matings.  In addition, depending on species, they may leave after mating, fly with and guard the female as she lays her eggs, or remain grasping the female as her eggs are laid.  His proximity to the female during egg laying prevents other males from removing his sperm.

Much of this information, as well as excellent photos for identifying dragonflies and damselflies, can be found in A Field Guide to the Dragonflies and Damselflies of Massachusetts, by Burne, Loose and Nikula. Another excellent Odonata resource is Dragonflies and Damselflies of the East by Dennis Paulson.  (Photo:  Mating darners (fast flying, large dragonflies), male above female)

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Shadow Darners Laying Eggs

9-4-17 darner laying eggs2 049A4462

The dragonfly family Aeshnidae consists of strong-flying dragonflies called darners, some of which are over three inches in length.  The majority of darners reach the peak of their population in August and early September.  Male Shadow Darners (Aeshna umbrosa) can be seen patrolling breeding sites a few feet over the water’s surface, searching for females and driving off competing males. Females can be observed repeatedly landing at the base of cattails, inserting their sharp-edged ovipositors and slicing open leaves, where they then deposit their eggs.  If you look at the bottom third of cattails at this time of year, near the water’s surface, you will find tiny, tan, vertical slits where dragonfly egg-laying has taken place. (Photo:  female Shadow Darner laying eggs)


Dragonflies Laying Eggs

8-27-14  black-tipped darner 133Never let it be said that Naturally Curious readers aren’t creative thinkers (see guesses on yesterday’s post) ! The vertical slits in the cattail leaves were made by female dragonflies that were in the process of laying their eggs. There are many different egg-laying strategies employed by dragonflies. Many females in the group of large, strong-flying dragonflies known as “darners” (such as the pictured Black-tipped Darner, Aeshna tuberculifera) use their lance-like ovipositors (see photo) to insert eggs into plants stems such as cattail, sphagnum moss, rotting wood or wet soil. However, most species of dragonflies possess non-functional ovipositors. The eggs of many of these species are washed off into water during flight as the female dips the tip of her abdomen into the lake, pond, river or stream.

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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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