Tuesday, November 10, 2015

Unexpected Pleasures of Dragonflying: The Flight of the Backswimmers

Betsy and I went to Mount Baker on October 16.  It was a beautiful, sunny day, with temperatures around 70 degrees, even though it was only in the 60s back home in Anacortes.

We usually see Ringed Emeralds there that time of year, but none were to be seen this time.  Instead, we saw numerous meadowhawks, which we usually don't see there at all.  There were three species of meadowhawks present: Cherry-faced, Saffron-winged, and Autumn.  Here they are.  First, the Cherry-faced Meadowhawk:

Notice the dark red color, with dark red stigma, mostly clear leading edges of the wings, and a dark stripe along the side of the abdomen.

Next, is the Saffron-winged Meadowhawk:

This meadowhawk sports yellowish leading edges to the wings, and light red stigmas with black borders along the long sides.

Lastly, was the Autumn Meadowhawk:

This is a bright red, spindly meadowhawk.  They also landed on each of us, one of its best field marks.  The other species of meadowhawks didn't land on us.

What was particularly interesting was that backswimmers were emerging from the water, drying out, then taking wing and smashing back into the water at a different location.  Here's a shot I got of one of the backswimmers.  It is in the background behind the Spotted Spreadwing in it's usual posture, upside down just below the surface of the water.  This is how they get their name.

Here is a backswimmer that has crawled up out of the water and is drying off so that it can take flight.

Here's a better shot of a backswimmer from the net:

These insects (true bugs) were taking off, flying all around, then crashing back into the water.  Sometimes they would do 2 or 3 "splash-dunks," similar to what dragonflies do, only in this case they were trying to break through the surface tension to get submerged with an attached bubble of air (plastron).  After a few splash-dunks, they would often hop around on the surface several more times until they finally got submerged and swam away.

We saw backswimmers hitting the water every minute or so, but on some occasions there can be "backswimmer rain", where they are hitting the surface continuously – as in a rain storm.  Sometimes the same type of phenomenon is seen with water boatmen, which are similar insects that swim right side up near the bottom.

We went to see dragonflies, but one of the great things about going out into the field is that you never know what unexpected pleasures may await you.

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