Peachtree borer
Synanthedon exitiosa
38 host plants
Last updated
You will see gummy masses containing sawdust and frass exuding from tree trunks near the soil line, typically three inches above to one foot below ground level. This is the first sign of peachtree borer damage. Larval galleries girdle the tree, causing foliage to yellow and wilt. Full-grown larvae are one to one-and-a-half inches long with whitish bodies and brown heads. Trees decline rapidly under heavy infestation.
Identify infested trees by observing gum exudation and frass at the base. Remove larvae by carefully probing with a flexible wire into galleries if trees are valuable and young. Wrap trunks with protective barriers in fall to prevent egg-laying. Apply pheromone sprays during summer flight period.
Quick Reference
Peachtree borer Adult emergence typically begins around 3872 GDD₃₂. As of May 13, 2026, Puget Sound stations range from 1906.2 to 2098.2 GDD₃₂, approximately 1774 units before the expected threshold.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of May 13, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,098 | Pre-season | Adult emergence | 1,774 |
| Kent / Auburn | 2,089 | Pre-season | Adult emergence | 1,783 |
| Seattle / UW | 2,063 | Pre-season | Adult emergence | 1,809 |
| Olympia / Tumwater | 2,025 | Pre-season | Adult emergence | 1,847 |
| Tacoma / Puyallup | 1,993 | Pre-season | Adult emergence | 1,879 |
| Bellingham / Whatcom | 1,972 | Pre-season | Adult emergence | 1,900 |
| Sequim / Rain Shadow | 1,906 | Pre-season | Adult emergence | 1,966 |
Source: Herms (OSU) phenological tables: 573 GDD₅₀ Greater Peach Tree Borer adult emergence, Dow Gardens MI 1985-1989 (Table 3). MSU Extension GDD of Landscape Insects: 575-710 GDD₅₀ adult emergence corroborates. Updated 2026-04-03. About GDD₃₂ →
The peachtree borer adult is a dark, bluish, clear-winged moth which somewhat resembles a wasp or hornet. The female, which has dark forewings and a red-orange band on the abdomen, lays eggs on the tree. Emerging larvae move to ground level or just below ground, where they burrow beneath the bark on the trunk and feed in the crown region. Signs of larval feeding include the presence near ground level of jelly-like gum mixed with dirt and pellets of excrement. Heavy infestations can weaken older trees, and foliage may be yellowed as if nitrogen deficient. Young trees may be girdled and killed.
Cultural Controls
- Several wasp species are parasitic on the larvae or pupae of the borer.
- Protect the base of the tree from larval entry by placing a cone around it before egg laying begins.
- Light metal or flexible plastic works.
- The cone should be pushed 1 to 2 inches into the soil and should fit snugly around the trunk at the top to prevent the tiny larvae from getting beneath it.
- Budding tape or other flexible material will help seal the top.
- Alternatively, if...