Peach Tree Crown Borer (Synanthedon exitiosa)
A pest that attacks Cherry, Plum, Peach, Apricot and other stone fruits.
The best way to detect these pests is to look for the physical signs which is often just below the soil grade on the root flare. It can also be slightly higher up on the trunk but this is less common. It appears as an amber to maroon colored jelly like mass where the larvae has tunneled into the wood. From April through September the larvae are often found in that mass or in the soil near the root flare. Other times up to 1/4" holes can be seen, sometimes inseries above the root flare where the larvae have tunneled into the tree.
Identification can be easily confused with the amber colored and often harder ooze on the trunks and limbs caused by Cytospora Canker. This is an entirely different problem resulting from a disease not a pest.
Peach Tree Borer adults fly from Mid-June through September laying eggs throughout their flight period. Females lay eggs on the lower trunk which hatch in about ten days. Eggs hatch into larvae that feed the rest of the warm season on the inner bark of larger roots and the low trunk. They hibernate in the soil near the trunk over the winter and return to tunneling and feeding in the early spring. They continue feeding until they pupate under the soil in a self made silk and frass sack sometime in may through June. They emerge as adult moths looking more like wasps than moths.
Damage occurs through tunneling in the root flare and larger roots by the larvae. They grow to about 1/4" diameter as larvae before pupating. Occasionally smaller (6"DBH or less) trees can be killed in a single season by girdling of the lower trunk from a heavy infestation.
The best management is through a Preventative Treatment application in early spring and again in mid summer. Once the larvae are in the trunk they cannot be controlled with pesticides very easily. Generally we strongly recommend preventative treatments to trees with a history of the Peach Tree Borer or for trees near other trees with current infection or that have a history.
Once the tree has larvae in it a strong wire can be used to stick in the borer holes and physically destroy the insect.
Moth Balls can be placed under the soil where borers are known to be and have been effective in killing the larvae under the bark. See CSU Fact Sheet #5.566 for more information on what type and how to apply moth balls. It is very important to get the appropriate type of moth ball and to place them properly.