Monday, January 24, 2011

Freeze Tolerance

 One snowy January day I was driving in Clearfield county when I saw a fence row of old wooden fence posts with barbed wire, so I stopped for this rural winter scenery shot.  Of course, it was the "weeds" that really caught my eye.

 Now, old fence posts and barbed wire are "cool", but golden rod galls are "way past cool".  In fact, this time of year they are frozen.

  The goldenrod gall fly larvae are freeze tolerant. In this bitter cold weather they are frozen solid.  If you drop a pea-sized larva on a hard surface, it "plinks".  But, warm one up, and soon it is moving around.  That is a very different winter survival strategy than the willow pine cone gall larvae.  Notice the larva's escape tunnel that it excavated in preparation for spring, when it will be a fly without a means of chewing out of its home.

 Chickadees and woodpeckers peck holes in the galls to feed on the larvae.

Fence rows are fascinating.

John Eastman gives more details about the goldenrod in the Book of Field and Roadside

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