Thursday, September 29, 2016

Canada Darner

I catch a few dragonflies in my bird nets. On 9 September 2016, I was at a loss to identify this darner. The ode seemed very dark. I know that dragonflies often lose their bright colors when they are cold or dead. But the weather was balmy and the darner was alive.

I called Scott King for help. To my surprise, he called it a Canada Darner, a species I have been seeking.  I thought they sported brilliant blue spots. That turns out to be in males. Females’ spots and stripes are either dingy blue or, as in this case, dull greenish. Both sexes of Canada Darners are especially liable to become dull-colored in low temperatures and brighten when the dragonflies are active as the day warms (Paulson).

My text books left me confused. I asked Scott what the clincher is for Canada Darner identification. He replied, “the darner ID is based on the length of segment 9, the segment with the ovipositor. For Aeshna canadensis [Canada Darner] it's short....just slightly longer than segment 10; for A. constricta [Lance-tipped Darner] it's long, at least twice the length of segment 10.” I am not sure how a fellow figures that out in the field. A net, I guess.

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