Rose Stem Girdler

How to identify it

• Adults are small, copper-green beetles in the metallic wood-boring beetle family.^[1]
• Larvae are cream-colored and flat-headed; their feeding leaves spiral scars or gall-like swellings on canes.^[1]
• Emerging adults leave a D-shaped exit hole in the cane.^[1]

Where it lives

Relatively new to the Pacific Northwest, it's increasingly reported from the south Puget Sound to Oregon's Willamette Valley and has been confirmed in the inland Northwest.^[1]

US map: public records from 17 states since 1990 (GBIF). View the map

Biology and life cycle

Adults most commonly emerge in early June in the Pacific Northwest, after warm, humid spring weather; cool or dry springs delay them.^[1]

Each adult lives about a week, feeding on leaves before laying eggs on the lower third of new canes or higher on older canes.^[1]

Eggs hatch within two weeks; larvae feed in the cane's vascular tissue through early summer and move into the pith by early fall, staying until the next year.^[1]

Damage and signs

• Girdled canes wilt from midsummer through fall and snap easily, especially under ripening berries, and damaged canes are more prone to winter injury.^[1]
• Losses are worst in young plantings and fall-bearing primocane varieties, and damage can be mistaken for normal cane dieback or Phytophthora root rot.^[1]

Health risk

It feeds on plants; the PNW Insect Management Handbook mentions no risk to people.^[1]

Control

Prevention

It often arrives on infested nursery stock, and wild roses and brambles along roads and waterways keep it around.^[1]

Sanitation

Thoroughly prune out and destroy damaged canes, which can cut populations by up to 80 percent; larvae rarely survive in canes pruned before late summer.^[1]

Canes pruned later, after larvae reach the pith, should be destroyed or tilled more than 2 inches under.^[1]

Pesticides

Sprays must target adult beetles before they lay eggs; treating before adults emerge doesn't work, and pollinator label guidelines matter because adults can emerge around bloom.^[1]

Common questions

Why are my raspberry canes wilting with spiral scars?

Rose stem girdler larvae feeding under the bark leave spiral scars and swellings and girdle the canes.^[1]

Does pruning help with rose stem girdler?

Yes. Thoroughly pruning out and destroying damaged canes can cut populations by up to 80 percent.^[1]

Sources

1. Pacific Northwest Pest Management Handbooks (OSU, WSU, University of Idaho), “Emerging Insect Pests in the Pacific Northwest: Rose stem girdler (2014; revised March 2025).” pnwhandbooks.org/insect/emerging-insect-pests/emerging-insect/rose-stem-girdler-2014 (accessed 2026-10-06)
2. iNaturalist, “Agrilus cuprescens taxon page (order and family).” www.inaturalist.org/taxa/212817 (accessed 2026-10-06)