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Honeylocust plant bug

Diaphnocoris chlorionis

3 host plants

Last updated

Data Coverage 2 of 6 dimensions
Host Plants
GDD Threshold
Peak Activity
Damage Severity
Monitoring
Regional Notes

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

Order
Hemiptera
Type
sucking-insect
Host Plants
3
GDD₃₂ Egg hatch early instar
1,799
Indicator: Blue false indigo first bloom

Honeylocust plant bug Egg hatch early instar typically begins around 1799 GDD₃₂. As of April 12, 2026, Puget Sound stations range from 1235.8 to 1375.3 GDD₃₂, approximately 424 units before the expected threshold.

Regional Season Tracker

GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 12, 2026
Station GDD₃₂ Current Stage Next To Go
Issaquah / East King 1,375 Pre-season Egg hatch early instar 424
Seattle / UW 1,348 Pre-season Egg hatch early instar 451
Kent / Auburn 1,308 Pre-season Egg hatch early instar 491
Olympia / Tumwater 1,292 Pre-season Egg hatch early instar 507
Bellingham / Whatcom 1,270 Pre-season Egg hatch early instar 529
Tacoma / Puyallup 1,258 Pre-season Egg hatch early instar 541
Sequim / Rain Shadow 1,236 Pre-season Egg hatch early instar 563

Source: UMD IPMnet catalog. Sources: UMD: extension.umd.edu. About GDD₃₂ →

Host Plants (3)