Codling moth
Emergence (est.) ActiveCydia pomonella
49 host plants
Last updated
Codling moth larvae burrow into apples and pears, creating holes filled with reddish-brown, crumbly droppings as they tunnel toward the core. You will see entry holes on the fruit surface, often on the side facing the trunk. Adult moths are gray-mottled and half to three-quarter inch long, with a distinctive dark coppery-brown band at the wing tip. Larvae are white to pink, about three-quarter inch when mature. Two generations per year occur; first emergence aligns with pink bloom.
Monitor at bloom using pheromone traps for spray timing. Remove dropped fruit and do not compost. Prune for air circulation. Apply spinosad or pyrethrin at early fruit development. Encourage natural parasitoids. Most home orchards succeed through trapping and sanitation alone.
Quick Reference
Codling moth Emergence (est.) typically begins around 995 GDD₃₂. As of May 13, 2026, all seven Puget Sound stations have passed this threshold (1906.2–2098.2 GDD₃₂), so Emergence (est.) is likely underway across the lowlands.
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 | Emergence (est.) | — | — |
| Kent / Auburn | 2,089 | Emergence (est.) | — | — |
| Seattle / UW | 2,063 | Emergence (est.) | — | — |
| Olympia / Tumwater | 2,025 | Emergence (est.) | — | — |
| Tacoma / Puyallup | 1,993 | Emergence (est.) | — | — |
| Bellingham / Whatcom | 1,972 | Emergence (est.) | — | — |
| Sequim / Rain Shadow | 1,906 | Emergence (est.) | — | — |
Source: 221 GDD50 is the standard codling moth first moth flight value, widely published by WSU Tree Fruit Research (Codling Moth Phenology Model), UC Davis IPM, and MSU Extension. Biofix is first sustained moth catch in pheromone traps; first egg hatch at biofix + 250 GDD50. Well-established value confirmed across multiple institutions. Sources: WSU: treefruit.wsu.edu. Additional sources: UC Davis IPM: UC Davis IPM (codling moth UC pest management guidelines); Rutgers: plant-pest-advisory.rutgers.edu (referenced); Wisconsin Extension: Wisconsin Extension (fruit/veg pest table). About GDD₃₂ →
Monitoring & Action
Pheromone traps (delta traps with codlemone lure) are the primary monitoring tool. Hang 1-2 traps per block at head height in the upper canopy by April (before moth flight). Check weekly. Establish biofix as the first date of consistent catch (2+ moths per trap on consecutive checks). Use degree-day accumulation from biofix to time management actions.
In commercial orchards: any trap catch establishes biofix and triggers spray timing. In home orchards: 5+ moths per trap per week indicates significant pressure. First egg hatch at biofix + 250 GDD50 is the critical spray window.
Larvae bore into fruit, typically entering through the calyx (blossom end) or side of the apple. They tunnel to the core, feeding on seeds and surrounding flesh. Entry holes may have reddish-brown frass (excrement) pushed out. When cut open, infested fruit shows brown tunneling and a hollowed-out core. External signs include small entry holes with frass, premature fruit coloring, and early fruit drop. A single larva can destroy the marketability of an apple. On pear, damage is similar but entry more commonly through the side.
Cultural Controls
- Remove and destroy infested fruit promptly WSU HortSense
- Remove brush, debris, and loose bark from orchard PNW Insect Management Handbook
- Trunk banding with corrugated cardboard PNW Insect Management Handbook
- Fruit bagging (paper bags over individual fruit) WSU Tree Fruit Extension
- Thin fruit to reduce contact between adjacent apples PNW Insect Management Handbook
Host Plants (49)
In the Puget Sound lowlands, codling moth pressure is moderate compared to the drier apple-growing regions east of the Cascades. The maritime climate slows degree-day accumulation, typically limiting the pest to two full generations. First moth flight in Kent usually occurs in mid to late May. Home orchardists with unmanaged apple trees are the primary population source in residential areas. Fruit bagging and trunk banding are practical and effective for the smaller trees common in home landscapes.
— Chris Welch, ISA Certified Arborist