Window Gnat Sylvicola fenestralis

This fly is a Window Gnat, so called because it is attracted to light and tends to appear on window panes. With its "leaded-window" pattern on its wings and a striped thorax, it looks a little like a small Crane Fly with short legs (short for a crane fly, long for a gnat).

It is a large, non-biting species of gnat.