Peach Tree Borer: Essential Guide to Prevention and Control

The Peach Tree Borer, scientifically known as Synanthedon exitiosa, is a notorious pest for peach and nectarine trees, as well as other stone fruits like apricot, cherry, and plum. This destructive insect is native to North America and has become a major concern for fruit growers in the region. The larvae of peach tree borers target the roots and lower trunks of their host trees, feeding on the growing tissue and inner bark, causing significant damage that can potentially lead to the death of younger trees.

Adult peach tree borers emerge between July and August, with females laying up to 500 eggs on tree trunks or in the soil near the tree trunk. Once the eggs hatch, the grub-like larvae begin their destructive journey, tunneling under the bark at the tree’s base and on larger roots. Damage caused by these pests can result in reduced fruit production, weaken the trees, and, in severe cases, kill the tree outright.

Effective management and control of peach tree borers are crucial to maintaining the health and productivity of fruit orchards. Some commonly used methods include regular monitoring, trapping, and the use of chemical control measures. By being proactive and vigilant, it is possible to minimize the damage caused by these menacing pests and ensure a healthy and fruitful harvest.

Peach Tree Borer Identification

Synanthedon Exitiosa

The Peach Tree Borer (Synanthedon exitiosa) is a significant pest that typically targets peach and nectarine trees but can also attack apricot, cherry, and plum trees¹. This insect is native to North America and can be found throughout the United States and Canada².

Moths and Wasps

Peach Tree Borers belong to the clearwing moth family. Although they resemble small wasps, they are actually moths².

Male and Female Peachtree Borers

• Male Peach Tree Borers have four narrow yellow bands on their abdomen and clear wings, making them look like small wasps².
• Female Peach Tree Borers are dark blue with two distinct orange bands on their abdomen, and opaque front wings².

Here is a comparison table for easy reference:

Life Cycle and Biology

Eggs and Larval Stage

• Eggs: Peach tree borers lay up to 500 eggs on tree trunks, in cracks, under bark scales, and in soil near tree trunks during July and August¹.
• Larvae: After hatching, they tunnel into roots and lower trunks, feeding on growing tissue and inner bark².

Pupal Stage

• Overwinter: Larvae partly grow in their burrow beneath tree bark during winter¹.
• Pupation: In spring, they complete their growth, construct a cocoon under the bark at or near soil level, and pupate¹.

Adult Stage

• Transformation: Adults emerge 17 to 25 days after pupation¹.
• Moths: Adult peach tree borers resemble paper wasps, with bluish-black females featuring an orange band on the abdomen³.

Damage and Infestation Detection

Soil Line and Lower Trunk

Peach Tree Borer primarily attacks the soil line and lower trunk area of peach, nectarine, cherry, plum, and apricot trees¹. The larvae cause damage by tunneling into the roots and lower trunks, feeding on the growing tissue and inner bark².

• Features:
  • Infestations often around the soil line and below
  • Larval damage to roots and lower trunks

Examples of infestation signs include holes, sawdust-like frass, and girdling on the roots and trunks².

Bark Wounds and Oozing

Bark wounds can be a sign of Peach Tree Borer infestation. Adult moths lay eggs on tree trunks, in cracks or under bark scales, and in soil near the tree trunk¹. When larvae feed on the inner bark, this can create wounds on the tree bark.

• Characteristics:
  • Wounds on tree bark
  • Larval feeding may cause oozing sap or gum

Oozing sap is another symptom to look for, as the larvae tunnel into sapwood³. If you notice oozing or sap leakage from wounds on the bark, it might indicate a Peach Tree Borer infestation.

Gum and Sapwood

The main symptom of Peach Tree Borer infestation in the sapwood and gum area is the presence of gummosis⁴. Gummosis refers to a tree’s production of gum or sap in response to stress, such as Peach Tree Borer damage.

• Features:
  • Gummosis near damaged areas
  • Presence of gum or sap around wounds

Damage to sapwood can be severe in young trees². If you spot gum or sap around wounds on branches or the tree trunk, it might be a sign of a Peach Tree Borer infestation⁴.

Monitoring and Control Methods

Pheromone Traps

Pheromone traps are an effective method for monitoring peach tree borer populations. They contain synthetically produced pheromones to attract male moths, helping to estimate the population size and the best timing for control measures. Key benefits include:

• Reducing reliance on chemical treatments
• Being non-toxic and eco-friendly

A downside of pheromone traps is that they only capture male moths, which may not reflect the actual population of larvae damaging the tree.

Mating Disruption

Mating disruption involves using pheromones to confuse male moths, impairing their ability to find females. This method has several advantages:

• Eco-friendly and non-toxic
• Compatible with Integrated Pest Management (IPM) strategies
• Reducing the need for chemical treatments

However, initial costs can be high, and its effectiveness may be limited in areas with high borer populations or in small orchards.

Chemical Treatments

Chemical treatments, such as insecticides, can provide effective control of peach tree borer. Two common insecticides include permethrin and carbaryl. These treatments should be applied when larvae are active and before they enter the tree to cause damage.

When using chemical treatments, it’s essential to apply them correctly and within the recommended guidelines to minimize the risk to beneficial insects and the environment.

Remember, maintaining healthy trees with proper pruning and watering can also help prevent infestations by making them less attractive to peach tree borers.

Preventing Peach Tree Borer Infestations

Tree Selection and Care

Selecting and properly caring for peach trees can help prevent damage from the Peach Tree Borer.

• Opt for resistant tree varieties, where possible.
• Ensure proper soil, water, and nutrient conditions for healthy tree growth.
• Prune damaged and diseased branches to help maintain tree health.

Tree Trunk Protection

Taking steps to protect tree trunks minimizes the opportunity for borers to infest.

• Apply a 50:50 latex paint solution to lower 12 inches of trunk (USU Extension).
• Inspect tree trunks regularly for signs of infestation, such as wounds or sawdust-like debris.

Cultural Practices

Preventive cultural practices can limit Peach Tree Borer populations.

• Monitor trees using pheromone traps to detect adult borer presence and determine an appropriate time to apply controls.
• Reduce overwintering larvae by removing and disposing of infested wood and debris.
• Minimize mechanical injury to the tree trunks.

Impact on Stone Fruit Trees

Peaches and Nectarines

The peach tree borer is a primary pest of peach and nectarine trees. The larvae feed on growing tissue and inner bark, leading to reduced crop bearing capacity due to lack of nutrient uptake¹. This can result in wilt, stunted growth, and even tree death.

Cherries

Cherry trees are also susceptible to peach tree borer infestations. The grub-like larvae can feed on the base and larger roots of the cherry trees, undermining the tree’s health².

Apricots

Peach tree borer attacks apricot trees as well. The larvae can bore underneath the bark, causing serious damage to the tree.

Plums

Plum trees, including flowering plum, can suffer from peach tree borer infestations. The insect pest targets the roots and the trunk’s base in plum trees, putting them at risk for a weakened structure and potential death³.

In summary, the peach tree borer impacts various stone fruit trees, including:

• Peaches
• Nectarines
• Cherries
• Apricots
• Plums

Common signs of peach tree borer infestation include:

• Wilt
• Stunted growth
• Tree death

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Peach Tree Borers Mating: Sexual Dimorphism

Sexual dimorphism or miscegnation?
A friend sent this salacious picture to me, but I was unable to identify the participants. Could you help him? ” Whilst mowing the lawn this morning I observed the two bugs in the attached photograph (actually I should say I observed the two attached bugs in the attached photograph). “They” were flying around in the same position as they are in the photo. The big guy seemed to be in control. They landed on a leaf and waited for me to go get my camera. I have no idea what’s going on here.
Chris Given”

Hi Chris,
This really is an excellent example of Sexual Dimorphism, not miscegenation. The Moths are Peach Tree Borers, Synanthedon exitiosa. The larger one in control is the female. This moth is a pest on peach trees as the caterpillars burrow in the wood causing considerable damage. Since we are able to post so few letters, we get very excited when we open excellent photos like your friend’s. Thanks for sending it our way.

Letter 2 – Female Peach Tree Borer

i can not figure out what this is. I believe its some kind of wasp moth?? It is not in any of my field guides. I ask you to help me out and let me know what it is if you can. Email me back.
Nate

Hi Nate,
Field Guides, like other research tools, are only effective if used properly. You would not be able to properly identify your Peach Tree Borer if you lived in Georgia and used a field guide to the moths and butterflies of Russia. You cannot properly use What’s That Bug? unless you provide information, yet you neglected to give us a location. Luckily, your female Peach Tree Borer is a very distinctive insect and it was easy enough for us to identify. It is one of the Sesiid Clearwing Wasp Moths. The species is quite unusual for its pronounced sexual dimorphism. The much smaller blue male moth looks like an entirely different species. According to BugGuide, the range includes eastern and central North America.

Letter 3 – Female Peach Tree Borer

Subject: What’s That Bug
Location: NH
August 7, 2015 3:12 pm
Saw this bug while watching humming birds on a lake in Barrington, NH
Signature: Ron

Dear Ron,
This is a female Peach Tree Borer, a wasp mimic moth whose larvae bore in the wood of peach and related stone fruit trees.  We just posted an image of a mating pair of this sexually dimorphic species.

Letter 4 – Female Peach Tree Borer

Subject: Black and orange flying bug
Location: Brooklyn, NY 11226
July 20, 2016 9:54 am
Hi Bugman,
There is a kind of flying bug around our yard in Brooklyn that appears regularly, freaking out our little 6 year old and his friends because they think it is a wasp. From the photo I took I see it is not a wasp but a black fly I think with an orange band around it’s thorax. I would like to know what it is and if it might bother the kids. ? Thanks!
Signature: Curiously yours, Kathleen Boyer

Dear Kathleen,
You and your son are both wrong.  This is a female Peach Tree Borer, Synanthedon exitiosa, a species of moth that exhibits pronounced sexual dimorphism, though both male and female Peach Tree Borers are wasp mimics which probably affords them significant protection from predators.  Since they are moths, Peach Tree Borers are harmless and pose no threat to your kids, but they might be compromising the health of your peach trees. 

Letter 5 – Mating Peach Tree Borers

What’s that Bug(s)
Bugman, I live in Rochester, NY and was walking through my front yard when this bug(s) flew at me at roughly eye level and then landed on my gutter. Any ideas what I am looking at here? A wasp maybe? Thanks,
Chris

Hi Chris,
What an awesome image you have of mating Peach Tree Borers, Synanthedon exitiosa. These are wasp mimic moths whose caterpillars bore into the wood of peach trees, causing considerable damage. This species exhibits marked sexual dimorphism. The female is the larger of the pair with the bright red stripe on her abdomen.

Letter 6 – Mating Peach Tree Borers

Subject: What is this?
Location: Denver Colorado
August 5, 2015 3:58 pm
Hi. My nephew sent me this picture from their backyard. Have to love summertime in the rocky mountains! No one know what this is. We hope you can help.
Thank you
Signature: Hillary Arellano

Hi Hillary,
Despite the lack of critical focus, the distinctive markings of these sexually dimorphic, mating Peach Tree Borers, Synanthedon exitiosa, are quite apparent.  The darker individual in the pair with the bright orange band is the female.  Peach Tree Borers are moths in the Clearwing family Sesiidae.

Letter 7 – Mating Peachtree Borers

Peach Tree Borers
Hello!
Thanks to your site, I now know that these are Peach Tree Borers. This amorous pair was spotted in Denver. Apparently they wandered over from the Western Slope, where we have terrific peaches. I thought I’d send along the photo if you wanted to use it. Thanks for the great site!
Chris Moore

Hi Chris,
Thanks so much for sending us your awesome photo of mating Peachtree Borers, Synanthedon exitiosa. The sexual dimorphism of this wasp mimic moth is quite remarkable as the larger darker female looks like a totally different species than her mate.