The peachtree borer is a clearwing moth pest of ornamental trees and shrubs. In particular, those in the genus Prunus are most impacted. The larvae of this insect feed on the inner bark of the host plants near the root crown and are capable of girdling the tree. Larvae (caterpillars) are cream colored with brown heads. Once mature, following approximately 7 instar stages, caterpillars pupate in their tunnels and the adult moths emerge around early July (records from New York). In North Carolina, they are said to pupate just beneath the soil line. In Florida, pupal cases are reported hanging from openings in the bark of the trunk, or within 2 inches of the host plant (presumably at the soil line). Pupae are dark brown or black in color, approximately 1/2 inch in length, with spines on their backs. Peachtree borer adult female moths are approximately an inch in length, dark metallic in color with a purple-ish hue, and a broad yellow band on the abdomen. Adult females lay 200-800 oval, reddish-brown, 1/2 mm long eggs on the trunk or lower branches of their host plants over a period of approximately 6 weeks. Eggs are laid in small groups. Adult males are different in appearance, looking more like a wasp with four narrow yellow bands on the abdomen and are slightly smaller in size than the females. Adults of this species do not feed. Newly hatched larvae of this species, unlike some other species of clearwing moths, are able to chew through the external bark to reach the phloem (Johnson and Lyon, 1991) where they feed; however reports from Florida find this species feeding in the cambium (Strickland, IFAS Extension). Other, similar species, rely on a wound or compromised location in the bark to enter the host plant to feed following egg hatch. This is why certain species of clearwing moth females preferentially lay their eggs near wounds, pruning cuts, or other cracks in host plant bark. In much of its range in the United States, there is a single generation per year. In warmer climates, 2 generations are possible. In Canada or colder climates, it may take 2 years to complete a single life cycle.
Larvae of this clear winged moth may girdle the host at the soil line. Unlike other related species, the peachtree borer prefers healthy hosts. Purple-leaf sand cherry (Prunus x cistena) is very susceptible to damage caused by this insect. Root feeding by this insect can reduce the vitality of the host plant, while trunk feeding may lead to tree girdling and death. Younger trees may be more susceptible, but both young and mature trees may show signs of yellowing of foliage, stunting of growth, and in stone fruit crops, a loss of productivity. Gum (sap) may be seen oozing from infested tree trunks, often filled with frass or soil; this is often seen at ground level on the trunk, or in the lower branches.
Pheromone traps are commercially available, and in orchards some use pheromones (sexually attractive chemicals) for mating disruption of the peachtree borer. Certain traps may perform better than others (ex. wing trap) and trap placement may affect the efficacy of the trap (ex. lower to the ground). Note that placing traps near susceptible hosts may attract egg-laying females to them. In managed landscapes, traps may be used to detect adult flights in order to better time chemical management applications if damage is extensive enough to warrant their use. Applications of insecticides may be made according to label instructions 8-16 days after adult moths are first detected in the pheromone trap. Note also that cloudy or overcast conditions may reduce the number of adult moths caught in traps in a single day. Pupal cases may be seen sticking from larval galleries in the trunk, or around the base of damaged trees.
Plant the correct plant on the correct site. Healthier plants that are maintained properly, while they may also be more attractive to this clearwing moth, are also better able to withstand infestation than host plants with other stressors. So as always, maintaining the overall health of the host plant is important. In fruit orchards (which this guide does not provide management information for), certain rootstocks may be less susceptible to this insect, indicating the possibility of certain host plant resistance. Studies have shown that weed removal around the base of trees (if thought of as a sanitation measure) did not help reduce peachtree borer infestation (Frank and Chandran, 2021). Frank and Chandran also hypothesized that weed removal would reduce the habitat for natural enemies of the peachtree borer, thus increasing their populations, but this was not supported by the data they collected. No effect was seen.
Entomopathogenic nematodes also used for other clearwing moths like lilac, rhododendron, and dogwood borers may also be applicable to the peachtree borer, however follow manufacturer instructions when selecting nematode species appropriate for this pest. Studies indicate that nematodes (Steinernema carpocapsae) applied in a preventative manner during the peachtree borer egg laying period can reduce insect damage to levels similar to what is achieved with recommended chemical insecticide treatments (Shapiro-Ilan et al., 2009). Previous research also showed that S. carpocapsae and Heterorhabditis bacteriophora species of nematodes can suppress damage caused by the peachtree borer in the field when applied curatively (once the insect infestation has already begun). Additional studies in British Columbia show that Heterorhabditis heliothidis is also effective at reducing populations of the peachtree borer (Cossentine et al., 1990). Field mice and rats are important predators of peachtree borer cocoons (Snapp and Thomson, 1943), and certain ant species are important predators of larvae and pupae. Telenomus quaintancei (parasitoid wasp impacting the eggs), Bracon (previously Microbracon) sanninoideae (parasitoid wasp impacting the larvae), and Villa (previously Anthrax) lateralis (parasitoid wasp impacting the pupae) have all been previously reported from peachtree borer populations (Snapp and Thomson, 1943). However, their total impact on peachtree borer populations may not yet be fully understood.
Azadirachtin (NL)
Bifenthrin (NL)
Chlorantraniliprole (NL)
Chlorpyrifos (N)
Cyantraniliprole (NL)
Dinotefuran (NL)
Emamectin benzoate (L)
Entomopathogenic nematodes (L)
Neem oil (NL)
Permethrin (L)
Spinosad (NL)
Apply chemical management options for newly hatching larvae and nematodes for already mining larvae.
Active ingredients that may be applied systemically include: azadirachtin (injection, soil drench), chlorantraniliprole (soil drench), cyantraniliprole (soil drench, soil injection), dinotefuran (soil drench), emamectin benzoate (injection), and neem oil (soil drench).
When used in a nursery setting, chlorpyrifos is for quarantine use only.
Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.
Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.
