Northwest berry Foundation

Management Detail

Raspberry Crown Borer

in Raspberries

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Latin name: Pennisetia marginata


Reason for Concern:
1) Larvae girdle new canes causing galls at the base.
2) Weakened canes often break during spring tying in.
3) Large larvae tunnel in fleshy root parts, further reducing cane vigor and yields.

Adult is a clear-winged moth resembling a yellow jacket wasp in color and size. Wingspan is about 1”; body is 25-30 mm long and black with 4 yellow horizontal stripes on the abdomen, stripes on the thorax, yellow legs, and feathery antennae. Unlike the short antennae of a yellow jacket wasp, RCB antennae curve outward from the head. Larvae, found in cane or root tunnels, have 6 short legs, and are white with brown heads. New larvae are 3 mm long; mature larvae-25 mm long. A hole at the plant base crown with sawdust-like frass at the entrance indicates RCB activity. An infested caneberry plant will wither and visibly wilt due to vascular tissue damage, especially in 2nd year infestation.

Life Cycle:
RBC completes a life cycle in 2 years. The female moth lays up to 140 reddish brown eggs most often on caneberry leaflet underside edges (2-3 per plant) in August or September. Once hatched (early fall), larvae migrate to the caneberry base where they dig in and form a blister-like covering or find a protected area in the bark and overwinter. In spring, RBC feeds on cane buds and burrows galleries through the plant crown, which causes swellings at or below the soil surface and the girdling of new canes. Burrowing continues through the 1st summer. The 2nd winter is spent in the roots; larva is white and about 0.4 to 0.9” (1.3–2 cm) long. Excavation continues the 2nd summer in the roots and crown. By midsummer the full-grown larva measuring 1” to 1.5” (2.5–3.3 cm) long undergoes a 2 to 3 weeks of pupation in the crown burrow and emerges as an adult moth. Adult moths are active from early August to late September and may be seen in daytime resting on foliage.



  • Examine weakened canes at the base crown for holes with sawdust-like frass near them and look for brittle canes in weakened areas.
  • If evidence of damage from this pest is found, there is no treatment for the affected plants, so they should be removed and promptly destroyed. A treatment program should also be implemented to prevent the infestation of this pest. Inaction can allow the Raspberry Crown Borer to spread quickly.
  • No viable effective pheromones are available for trapping this pest at this time.

Cultural Controls:

  • Dig out and remove infested canes.


For information about chemical controls, check with our Pesticide Guide.


photo by J. Troubridge

photo by K. Gray

photo by K. Gray

photo by W. MacDiarmid

photo by T. Peerbolt


photo by T. Peerbolt


photo by T. Peerbolt


Damage done by raspberry crown borer - photo by T. Peerbolt

Damage done by raspberry crown borer - photo by T. Peerbolt

Damage done by raspberry crown borer - photo by T. Peerbolt

Trap and lure - photo by T. Peerbolt


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