A couple newsletters ago, I listed some White Birch that was peppered with "bug track" and said that
although we found these particular boards attractive, White Birch veneer buyers don't like it. Lindy asked me why and I couldn't
come up with an answer. So, as I so often do, I contacted our county forester who has helped me repeatedly in researching such
Bug track, or worm track, or sometimes termed flex, is caused by annual attacks from a small fly and
results in orange to reddish to brownish dashes in the wood of White Birch. Similar insects can cause the same in White Ash
(Glass Fly), Black Cherry (gum), and Soft Maple.
Bug track is a surface defect only and will not affect any finishing; i.e., paint, stain, oil, etc.
other than show the "defect" in a clear finish. The reason that veneer buyers do not like it is that often times they try to
substitute White Birch for the more expensive Yellow Birch. The catch is that Yellow Birch is not affected by these insects and
consequently never shows any track. Paper Birch veneer logs without the bug track may command a price of $2 / bf whereas the same
quality log with the track will only sell for $.80 / bf.