This species is well known to peach growers in the southern and eastern regions of the US, but will occur as far north as eastern Canada. It can also be a pest in ornamental landscapes, particularly on flowering cherry (multiple species of Prunus). Adult lesser peachtree borers are moths that resemble wasps, with transparent wings. Adult male moths are approximately 1/2 inch in length with a narrow black band on the tip of the front wings. They are similar in appearance to the peachtree borer, Synanthedon exitiosa. When mature, larvae are 3/4 - 1 inch in length, white, with brown heads. Larvae have prolegs with crochets, or rows of tiny hooks, on the bottom. Larvae overwinter beneath the bark, typically near branch crotches. They may overwinter at various sizes/stages, maturing in the spring. Larvae chew an exit hole in the bark, spin a cocoon, and pupate often in a small cavity. 3-4 weeks after pupation, the adult moth emerges, leaving behind the empty pupal case/skin projecting from the cavity. Adult lesser peachtree borer moths fly during the day, unlike most moth species. Adult female moths may lay several hundred round, reddish-brown eggs (in groups of 400) in bark cracks, scales, and near wounded or cankered areas. This species is attracted to previously infested trees or those that have been wounded, as this helps aid the larvae in entering the tree to feed. Eggs may take 7-10 days to hatch, at which point tiny larvae will move to the inner bark to feed. Larvae are found in the inner cambium and may eventually girdle the conductive tissue of the tree. Depending upon geographic location, two complete generations occur per year with the possibility of a partial third generation in warmer locations.
Frequently found at points such as branch crotches, trunk wounds, or fungal cankers. Larvae need a frost crack, canker, wound, or pruning scar to be able to enter the phloem to feed. Damage from the lesser peachtree borer usually leads to suckering or adventitious growth. Injury from this insect may also result in the formation of amber-like gum on the outside of the bark, a sign of activity often referred to as "gummosis". Sometimes, gummosis will contain red frass which exudes from borer galleries beneath the bark. These galleries typically occur in branch crotches of larger branches or the upper trunk. In heavy infestations, branch dieback may occur. Older trees are typically more likely to be infested with this insect than younger trees, as they are more likely to have accumulated wounds, pruning cuts, cankers, and other potential points of entry over their lifetime.
Visual survey for gummosis or frass in branch crotches is one way to monitor for the presence of the lesser peachtree borer. If the gummosis does not contain the reddish frass, wood chips, or sawdust-like material, it may be caused by something other than a borer. Look also for shed pupal skins left behind in cankered areas. Some recommendations state that if fewer than two pupal skins are seen per tree, management may not be necessary until the second generation in late summer. Pheromone traps may be used to detect adult moth emergence, which in Massachusetts may occur from June 1st to late August. In orchards, recommended timing for installation of pheromone traps is at petal fall. If monitoring for lesser peachtree borer, orchard recommendations include that management may not be necessary until more than 10 adult moths are caught in the traps per week. In ornamental settings, this threshold may be lower. Pheromone traps can be used to time bark spray applications, with suggested timing being 8-10 days after the first adult moths are trapped. Continue to monitor adult flight through the end of August to determine if multiple applications are necessary. For monitoring and management recommendations in orchards and fruit production, visit: New England Tree Fruit Management Guide.
Any practices that prevent cankering, wounding, or scarring (including pruning scars) particularly during the adult moth flight period will help prevent lesser peachtree borer infestation. Practices that promote tree health and vigor are also encouraged as preventative measures for wood-boring insects.
Natural enemies present in landscapes that might reduce lesser peachtree borer populations are rarely discussed. Certain species of nematode that can be purchased and used as a biological insecticide have been studied to manage the lesser peachtree borer. Nematodes in the genera Heterorhabditis spp. and Steinernema spp. have been shown to be effective, if measures are taken to protect the nematodes from UV radiation and drying out. Researchers have achieved this in some studies using a protective gel coating over the nematode application and the application may be at least as effective as chemical standards (Shapiro-Ilan et al., 2016).
Abamectin (NL)
Acephate (NL)
Azadirachtin (NL)
Bifenthrin (NL)
Carbaryl (L)
Chlorantraniliprole (NL)
Chlorpyrifos (N)
Cyantraniliprole (NL)
Emamectin benzoate (L)
Entomopathogenic nematodes (L)
Flonicamid+cyclaniliprole (N)
Neem oil (NL)
Permethrin (L)
Spinosad (NL)
Thoroughly wetting the trunk and scaffold limbs when making contact insecticide applications (bark sprays) is necessary to achieve proper coverage. Target the newly hatched larvae while crawling on the bark surface.
Active ingredients that may be applied systemically include: azadirachtin (injection, soil drench), cyantraniliprole (soil drench, soil injection), imidacloprid (soil drench), 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.
