The red oak borer is a serious pest of trees in the red oak group. It
ranges throughout eastern North America wherever host species grow. It
is estimated that defects caused by larval tunnels in the sapwood and
heartwood of host trees costs the hardwood timber industry millions of
dollars each year.
[Illustration: Adult red oak borer.]
Eggs of the red oak borer are laid during early and mid-summer in bark
crevices or under patches of lichen on host trees. After hatching,
larvae bore into the inner bark region where they feed until mid-summer
of the next year. This feeding in the inner bark causes characteristic
catfaces or bark pockets. Once larvae enter the wood they bore upward
through the sapwood and into the heartwood and pupate behind a plug of
excelsior-like frass. The larval galleries are from one-fourth to
one-half inch in diameter, and six to ten inches long. Usually the
galleries are within six inches of the center of the tree. The adult
emerges at the lower end of the tunnel, using a hole cut through the
bark by the larva just prior to pupating. Adults emerge in June and
July. The timing of the two-year life cycle of the red oak borer is such
that the adult population is greatest in odd-numbered years.
Generally, borers such as the red oak borer infest trees of poor vigor.
It is possible, therefore, to reduce borer populations by maintaining
vigorous stands and by removing cull trees.
[Illustration: Red oak borer attack on Nuttall oak.]