Friday, July 22, 2011

The Devil's Big Blue Darning Needles

Regina, SK: An awakening of Big Blue Darner dragonflies has made Saskatchewan's mosquito invasion this summer far more bearable. Not only do these dragonflies eat huge quantities of bugs, but they are also graceful and entertaining to watch.

Identification of this species comes from a CBC Radio interview about dragonflies a few days ago with author/aquatic entomologist David Halstead (Dragonflies and Damselflies in the Hand), who said that the big dragonflies we are seeing now are, yes, Big Blue Darners.

And most of the dragonflies I've been seeing (in addition to smaller Meadowhawks) are certainly big. Individuals of this species look at least three or four inches long, with a wingspan even longer. Swarms, as well as single dragonflies, are easily visible dozens of metres away. And while these dragonflies look black from a distance, blue bands and spots emerge around the abdomen and upper body when they are close-up and glinting in the sun.

However, there are many kinds of darners, so after "Big Blue" — which sounds like a generic description if I've ever heard one — I'm stumped. (I've tried comparing images — mine with web photos — and the closest I've come is a Canada Darner; the body marking, at least, are almost identical.)

Dragonfly on stucco - photo by Shelley Banks
One of the big guys -- they look about  four inches
long to me! (Taken on Anne's stucco wall) © SB
Regardless of identification — although I'd like to think I'm right — darners are fascinating because of their folkloric associations. As this online guide from West Virginia University explains:
Darners, a dominant family today, and considerably advanced in color and habit over more primitive families, are large swift flying dragonflies often seen in late summer and fall.
They are the devil's darning needles reported by many a folktale as responsible for sewing shut the mouth, ears, and eyes of disobedient children. (From: Dragonflies: Introduction to Dragonflies and Damselflies) 
I also find dragonflies interesting because unlike mosquitoes, they are not instant summer creatures.

In a Saskatoon StarPhoenix story last week, "Rise in dragonfly numbers helps battle mosquitoes", retired University of Saskatchewan biologist Cedric Gillot explains that it takes two or three seasons for the wet habitat  — and the dragonflies themselves — to develop.

So the more rain we have, the more wetlands that are developed. And the more wetlands and ponds, the greater number of mosquitoes — and the better chance we have of a surge in the dragonfly population to devour them.

The balance of nature, with a little help from the Devil's darning needles.


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