Peachtree Borer
Synanthedon exitiosa
A clear-winged moth whose larvae bore into the lower trunk and roots of peach, cherry, plum, and other stone fruit, feeding on the inner bark and girdling the tree. One of the most damaging pests of backyard stone fruit, the peachtree borer can weaken and kill a tree from the base, betrayed by gum and frass oozing near the soil line.
🔎 How to spot it
The clearest sign is masses of gummy, frass-filled ooze at the base of the trunk, near or just below the soil line, where the larvae tunnel. The larvae are cream-colored caterpillars up to about an inch and a quarter with brown heads, found under the bark at the crown. The adults are striking clear-winged moths that look like wasps; females are dark blue with an orange band, males narrower with yellow bands.
🥀 Damage it causes
The larvae tunnel through the inner bark of the lower trunk and large roots, and their feeding girdles the tree, cutting off the flow of water and nutrients. Young trees can be killed outright, while older trees are weakened, decline in vigor and yield, and become prone to other problems. Infestations are most damaging at and below the soil line where they are hard to see.
🛡️ Prevent it
Inspect the lower trunk and crown each year for the gummy, sawdust-laced ooze that signals borers. Keep trees vigorous and avoid wounding the lower trunk with mowers and trimmers, since wounds and stress attract the moths. Hang pheromone traps to time the adult flight, and keep the trunk base clear of weeds and mulch so borers cannot hide.
🧯 If it is already here
For a few borers, worm them out by hand: probe the gummy holes with a flexible wire to kill the larvae under the bark in late summer or early spring. The main chemical control is a trunk-targeted insecticide applied to the lower trunk and crown timed to the adult flight, after egg-laying and before larvae bore in, as indicated by pheromone traps; follow the label. Remove and destroy severely girdled young trees.
💡 Good to know
Because the borers work at and below the soil line, the gummy frass-laced ooze at the base of a stone fruit tree is the key warning sign, distinct from the clear, clean gum a tree exudes from ordinary stress or injury. Timing any control to the adult moth flight, tracked with pheromone traps, is what makes it effective.
🌱 Plants it attacks
17 plants in the library can be attacked by this pest
For educational and informational purposes only. Pest control advice is general guidance drawn from university cooperative extension sources; always identify a pest positively and read and follow the label on any product before use, especially around food crops, children, and pets.