Spotted Lanternfly
Lycorma delicatula
0 host plants
Last updated
Quick Reference
Spotted Lanternfly First adult activity typically begins around 3700 GDD₃₂. As of April 17, 2026, Puget Sound stations range from 1302.4 to 1445.4 GDD₃₂, approximately 2255 units before the expected threshold.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 17, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,445 | Pre-season | First adult activity | 2,255 |
| Seattle / UW | 1,417 | Pre-season | First adult activity | 2,284 |
| Kent / Auburn | 1,385 | Pre-season | First adult activity | 2,315 |
| Olympia / Tumwater | 1,363 | Pre-season | First adult activity | 2,337 |
| Bellingham / Whatcom | 1,343 | Pre-season | First adult activity | 2,357 |
| Tacoma / Puyallup | 1,328 | Pre-season | First adult activity | 2,372 |
| Sequim / Rain Shadow | 1,302 | Pre-season | First adult activity | 2,398 |
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 spring), especially on A. altissima, pallets, shipping containers, and vehicles from infested states. Sticky tree bands (circle traps) on host tree trunks to intercept nymphs walking upward, deployed by May. Pheromone traps not yet commercially available. Report any sighting to state agriculture department. WSDA and ODA run annual trapping surveys at high-risk introduction points.
Any confirmed detection in the PNW warrants immediate reporting to WSDA (WA) or ODA (OR). This is a quarantine pest in both states. Zero-tolerance threshold: a single confirmed specimen triggers regulatory response.
Feeds by piercing plant tissue with stylet mouthparts and extracting phloem sap. Heavy feeding causes weeping wounds on trunks, wilting, leaf curling, and dieback. Excretes large quantities of honeydew, promoting sooty mold growth on leaves, fruit, and surfaces below feeding sites. Honeydew accumulation also attracts yellowjackets and other stinging insects. Severe infestations can weaken and kill grapevines and young trees; vineyard losses in Pennsylvania have been significant (USDA APHIS). Feeding on fruit crops reduces fruit quality.
Cultural Controls
- Inspect and scrape egg masses
- Remove Ailanthus altissima (tree of heaven)
- Inspect incoming goods and vehicles from infested states
- Report all sightings
Not confirmed established in Oregon or Washington as of early 2026. OSU researchers developed a forecast model (DDRP platform, available via USA National Phenology Network) mapping SLF establishment risk; the Puget Sound lowlands, Willamette Valley, and Columbia River corridor are within the predicted climatically suitable range. Climate suitability modeling shows mean temperature of the driest quarter is a key predictor of establishment potential (Wakie et al. 2020). Ailanthus altissima, the preferred reproductive host, is present along the Columbia River (first recorded in Oregon in 1904 in Wasco County). ODA has intercepted dead adults and one live egg mass on incoming cargo from infested states but has not documented an established population. WSDA maintains active surveillance (trapping program); after two 2025 survey efforts, no SLF were confirmed, and an iNaturalist report was not verified. Report suspected sightings to WSDA at agr.wa.gov/lanternfly or 1-800-443-6684, or in Oregon to ODA. If found, do not release; photograph, collect specimen if possible, and note exact location.