Entrance and emergence holes in white oak.
RED OAK BORER, Enaphalodes rufulus (Hald.)
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.
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.
Red oak borer attack on Nuttall oak.