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 sna