Friday, November 6, 2009

A Tiny Moth on an Unseasonably Warm Day

I spotted a very small (about an inch long) whitish insect - a flitting along the Chippewa River State Trail today.   A butterfly, or moth?

Every time it stopped, I would hurry over with my little Sony CyberShot, bend down, and ...  off it would fly again.  I was about ready to give up, when it flew down and landed on a plant.

If I could take a photo, I might be able to figure out what it is.  I snapped one photo, and off it flew.  In the camera, it looked much darker - but maybe good enough for an identification.

After I got home and downloaded it, I went to my favorite web page, The Bug Guide.  I thought I had it figured out - a dogbane saucroboyts, but I wasn't quite sure.  So I sent an email off to Phil Pelliteri at the University of Wisconsin.  He suggested a late season inchworm, a geometrid.

I went back to the bug guide, and uploaded my photo.  Charlie Eiseman responded with Bruce Spanworm.  Looks right to me.

The caterpillars of this species feed on the leaves of hardwood trees.  Sugar Maples and Aspens are among their favorites.  By the end of June they pupate on the ground and emerge as adults in October or November.  The wingless females lay their pale green eggs singly, in the crevices of tree bark.

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