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Archive for August 31, 2015

Black-tipped Darner

black-tipped darner IMG_3123There are two darners that look very much alike, the Black-tipped (Aeshna tuberculifera) and the Shadow Darner (Aeshna umbrosa). The differences are somewhat subtle, so I spent a great deal of time identifying the egg-layers that I photographed for today’s post, vacillating back and forth between the two species. I finally zoomed in on one photo and determined that the lateral stripes on its thorax were outlined in black, making it a Black-tipped Darner (Shadow Darners lack this outline, and lack coloring on the last abdominal segment). That said, while I knew the identity, I neglected to make sure my post reflected this, and once again, a reader was kind enough to point this out. Thank you, Mike Blust!


Darners Laying Eggs

9-1-15 dragonfly laying egg 135Females of different species of dragonfly have different techniques for laying their eggs. Most skimmers, cruisers and clubtails dip the tip of their abdomen to the surface of the water while hovering or flying, and release their eggs. Most darners, such as the Shadow Darner (Aeshna umbrosa) pictured, have a sharp-edged ovipositor with which they slit open a stem or leaf of a plant on or near the water. They then push their egg into the plant tissue exposed by the slit. Because they are stationary during this process, female darners are vulnerable to predation by fish and frogs at this time. A close look at the bottom third of cattail leaves this time of year will tell you whether or not darners are in the vicinity, as the slits they make are very apparent, appearing as thin, tan, 1/2″ vertical lines.

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