Peachtree Borer,
Synanthedon exitiosa (Say)

I. Introduction: The peachtree borer (PTB) is a native North American pest that has been known since colonial times. It is generally not as important as the LPTB in the mid-Atlantic region, however, localized severe infestations have occurred. Unlike the LPTB, PTB can become established in a healthy tree and can cause death of young trees in a single season.

II. Hosts: This insect is a most serious threat to peach and nectarine, but all commercial stone fruits and wild plum, cherry, and related plants are susceptible to injury.

III. Description: Adults are clear-winged, metallic blue-black moths that resemble wasps. The male is similar to the lesser peachtree borer, but larger and with narrow yellowish bands on the third through the fifth or sixth abdominal segments (right in photo above). The female is slightly larger than the male, with a broad orange band on the fourth and fifth abdominal segments (left in photo above). The female has dark blue and opaque forewings and clear hindwings, whereas both wings are clear with dark borders and a transparent amber sheen in the male. The wingspan is 1/2 - 1 1/3 inches (1.4- 3.3 cm). Eggs are oval, cinnamon to rust brown, and less than 4/100 inch (1 mm) in size. The larva is white with a yellowish-brown to dark brown head and up to 1 1/6 inches (38 mm) long when full-grown (Plate 124). The pupal stage (Plate 124) is brown and 5/8 - 3/4 inch (16-19 mm) long, with the orange band visible on the female just before emergence. A rust-brown cocoon is constructed of frass and wood and soil particles held together with silken threads.

IV. Biology: The PTB overwinters as various larval stages in burrows under the bark at or near ground level. Larvae resume feeding and complete their development in the spring and early summer. A cocoon is constructed in an upright position just beneath the soil at or near the tree trunk. After a 3 to 4 week pupation period the adult emerges, leaving the empty pupal case protruding from the cocoon. Moth flight occurs during June to September, there being one generation per year (figure). Moths are active during the day, with females mating and beginning to lay eggs on the day of emergence. Each female deposits an average of 400 eggs within a few days on the trunk and on weeds and soil around the base of the tree. Adult females live only for about 1 week. Eggs hatch in about 10 days and larvae enter the tree through cracks or wounds in the bark near the soil line. Larvae feed and develop in the cambium layer until winter.

V. Injury: The larval stage feeds in the inner bark and cambium tissue of trees within a few inches above to below ground level. Feeding may also occur on large roots near the soil surface. Evidence of infestation consists of frass and fine wood borings mixed with gum at the base of trees (Plate 125). Young trees may be completely girdled in a single season, resulting in death. Older infested trees are less vigorous and productive, and often succumb to other insects, diseases or winter injury before girdling causes death.

VI. Monitoring: Install a pheromone trap at shuck-fall for monitoring male PTB emergence. Inspect the base of trees for an exudation of gum containing frass and sawdust (Plate 127). Determine the average number of cocoons and empty pupal cases in the soil at or near the base of the tree. A management strategy is recommended for trees up to three years old if any evidence of PTB infestation is detected. In older orchards, an average of more than one cocoon and/or empty pupal case per tree would warrant treatment. Experience has shown that populations seldom need treatment when trap catches peak at less than 10 moths/trap/week.

For monitoring male PTB emergence, monitor pheromone traps weekly and inspect the base of trees for an exudation of gum containing frass and sawdust (Plate 127). Determine the average number of cocoons and empty pupal cases in the soil at or near the base of the tree. A management strategy is recommended for trees up to three years old if any evidence of PTB infestation is detected. In older orchards, an average of more than one cocoon and/or empty pupal case per tree would warrant treatment. Experience has shown that populations seldom need treatment when trap catches peak at less than 10 moths/trap/week.

Mating Disruption is available for peachtree borer through Pacific Biocontrol.


See the Virginia Tech Factsheet, and f actsheets from Kentucky, New York, Texas, and Michigan


This is taken primarily from a chapter by H. W. Hogmire and D. F. Polk on peach indirect pests, reprinted with permission from Mid-Atlantic Orchard Monitoring Guide, published by NRAES, 152 Riley-Robb Hall, Ithaca, New York 14853-5701. (607) 255-7654.
Back to Virginia Peach page
Back to Virginia Fruit Page