Insects, Pests, Diseases & Weeds
Many types of insect and mite pests can attack trees in home landscapes. Although feeding damage from most of these pests is aesthetically displeasing, it does not cause severe damage to the tree. Even after total defoliation by caterpillars, most trees will put out a new flush of foliage. Several consecutive years or more of defoliation are needed to cause a serious decline or death of most trees. Also, defoliation late in the growing season is much less detrimental to tree health than that occurring in spring or early summer.
Conversely, some pests can routinely cause significant damage and even death of the tree. Insect borers are one such group. Some insect borers girdle the trunk by destroying vascular tissue beneath the bark. This can effectively limit the upward flow of water and nutrients to the canopy and the flow of photosynthesis products to the roots for storage. Other insect borers can riddle the trunk or branches with tunnels, weakening them so that they will snap in a windstorm. Some borers can directly transmit disease. Open wounds in the bark made by borers also can be an entryway for disease. The four common types of tree borers to be discussed are clearwing borers, flatheaded borers, roundheaded borers and the pyralid moth borers.
"SP547 Common Tree Borers in Tennessee," The University of Tennessee Agricultural Extension Service, SP 547 - 15M - 12 - 00 R12 - 4910 - 21 - 001 - 01, http://trace.tennessee.edu/utk_agexfores/97