Honeylocust plant bug
Diaphnocoris chlorionis
3 host plants
Last updated
Honeylocust plant bugs appear on honeylocust foliage in late spring and early summer, feeding by piercing plant tissue and sucking sap. The small bugs (less than 0.25 inch) are brown or darkly colored and congregate on younger leaves. Feeding damage causes yellowing, stippling, and leaf curling; affected foliage may eventually brown and drop. Heavy infestations reduce tree vigor and aesthetic appeal.
Monitor honeylocust trees from late May through July for plant bug presence and early stippling. Remove heavily infested shoots by hand if populations are light. For active populations, apply insecticidal soap or neem oil targeting nymphs and adults. Horticultural oil in late winter targets overwintering adults. Most infestations self-regulate above 80 degrees Fahrenheit.
Quick Reference
Honeylocust plant bug Egg hatch early instar typically begins around 1799 GDD₃₂. As of June 3, 2026, all seven Puget Sound stations have passed this threshold (2435.5–2672.8 GDD₃₂), so Egg hatch early instar is likely underway across the lowlands.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Jun 3, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,673 | Egg hatch early instar | — | — |
| Kent / Auburn | 2,665 | Egg hatch early instar | — | — |
| Seattle / UW | 2,610 | Egg hatch early instar | — | — |
| Olympia / Tumwater | 2,570 | Egg hatch early instar | — | — |
| Tacoma / Puyallup | 2,535 | Egg hatch early instar | — | — |
| Bellingham / Whatcom | 2,533 | Egg hatch early instar | — | — |
| Sequim / Rain Shadow | 2,436 | Egg hatch early instar | — | — |
Source: UMD IPMnet catalog. Sources: UMD: extension.umd.edu. About GDD₃₂ →