| The peachtree borer, Synanthedon exitiosa, attacks
stone fruits, especially peaches and nectarines.
Damage is found either in the crown area or the
lower part of the trunk near the soil line. These pests
can girdle and kill healthy young trees. Older trees
are sometimes attacked, but they usually tolerate the
damage unless there are many larvae or a tree is
attacked several years in a row.
Symptoms and Diagnosis
Holes appear in the lower part of the trunk or in the
upper trunk and lower crotches. A thick, gummy or
jellylike sap often oozes from these holes. Sawdust
may surround the holes or collect at the base of the
tree. In mid- to late-summer, some of the leaves and
branches may wilt. Severely affected trees may die.
Life Cycle
The adult peachtree borer is a steel blue to black
moth that resembles a wasp. The adult borer
emerges in the late spring and early summer. The
clear-winged female moths lay their eggs on the
bark at the base of tree trunks in mid- to
late-summer.
Hatching larvae tunnel into the tree at or slightly
below ground level. The larvae are dull white to
light brown or pinkish worms with a darker-colored
head. They feed in the crown area and burrow up
into the tree, leaving small piles of reddish-brown
frass (waste material of the borer) at their burrow
entrances. The tunnels that the larvae make interfere
with the circulation of water and nutrients, causing
twigs and branches to wilt and die. These borers
feed throughout the winter and into the spring. The
borers pupate in early to midsummer in cocoons
located at the base of the tree or just inside their
tunnels. Adult moths emerge 20 to 30 days later. The
peachtree borer has only one generation a year.
Integrated Pest Management Strategies
1. Mechanically remove borers. If only a few trees
in a backyard situation are infested, you can
remove borers through a technique called
worming. Remove the soil from around the base
of infected trees, and use a pocketknife or some
other pointed instrument to dig the larvae out. Be
careful; it is possible to seriously injure the tree if
too much bark or wood is removed. Individual
borers may be killed by inserting a wire into
their holes.
2. Keep trees vigorous. Use good sanitation
practices, adequate irrigation, and good pruning
techniques to keep trees healthy.
3. Avoid wounds or mechanical injury of the trunk and upper branches. Wounds can provide entry points for borers.
4. Use insecticides if necessary. Spray or paint only the trunk and lower limbs with either carbaryl (Sevin) or endosulfan (Thiodan) in the first half of May and again in the first half of August as a preventative. Permethrin can be used on non-edible plums. To avoid killing bees, do not spray during bloom.
5. Examine your trees yearly.The best time to check
your trees is in the fall. Look for small accumulations of frass on the lower tree trunk,
especially on trees that appear weakened. | 
