Spotted Lanternfly
Lycorma delicatula
0 host plants
Last updated
Quick Reference
Spotted Lanternfly First adult activity typically begins around 3700 GDD₃₂. As of May 29, 2026, Puget Sound stations range from 2301.6 to 2526.1 GDD₃₂, approximately 1174 units before the expected threshold.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of May 29, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,526 | Pre-season | First adult activity | 1,174 |
| Kent / Auburn | 2,512 | Pre-season | First adult activity | 1,188 |
| Seattle / UW | 2,465 | Pre-season | First adult activity | 1,235 |
| Olympia / Tumwater | 2,426 | Pre-season | First adult activity | 1,274 |
| Tacoma / Puyallup | 2,391 | Pre-season | First adult activity | 1,309 |
| Bellingham / Whatcom | 2,391 | Pre-season | First adult activity | 1,309 |
| Sequim / Rain Shadow | 2,302 | Pre-season | First adult activity | 1,398 |
GDD source: UMD IPMnet Pest Predictive Calendar (Gill & Klick). Base 50°F, mid-Atlantic climate. Converted to GDD₃₂ for Western WA. About GDD₃₂ →
Monitoring & Action
Visual inspection for egg masses on smooth surfaces (fall through
Any confirmed detection in the PNW warrants immediate reporting
Feeds by piercing plant tissue with stylet mouthparts and extracting
Cultural Controls
- Inspect and scrape egg masses Penn State Extension
- Remove Ailanthus altissima (tree of heaven) Penn State Extension
- Inspect incoming goods and vehicles from infested states USDA APHIS; WSDA
- Report all sightings WSDA; ODA
Sources & References
Primary: Leach et al. 2023 — Seasonal activity of spotted lanternfly (Hemiptera: Fulgoridae) in Southeast Pennsylvania. Environmental Entomology 52(6):1108-1119. doi:10.1093/ee/nvad093
- OSU Extension — Spotted lanternfly forecast model (DDRP platform)
- OSU Extension — Unconfirmed SLF sighting
- OSU Extension — Spotted Lanternfly fact sheet (EM 9312)
- PNW Handbooks — Emerging Insect Pests
- USA National Phenology Network — SLF Forecast Maps (base 50°F; egg hatch 364 GDD, adult emergence 1934 GDD)
- UMD Extension IPMnet Pest Predictive Calendar (Gill & Klick) — egg hatch 270 GDD₅₀, first adult 1112 GDD₅₀
- WSDA — Spotted Lanternfly page
- USDA APHIS — Spotted Lanternfly