The rednecked cane borer is a beetle that infects brambles such as black raspberries and blackberries. The beetles attack foliage, and the larvae cause galls that split the bark of the cane.

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Appearance:

  • Adults are small metallic wood-boring beetles, with a reddish area behind the head.

  • Larvae are white, legless, and flat behind the head

  • Pupae are about the same length and shape as adults

  • Overwinters in the canes as larvae

Damage:

  • Adult feeding leaves irregular holes in the foliage.

  • Larval feeding causes galls that can cause bark to split and stems to break.

  • Infected canes can die or become weak and unable to support the fruit.

  • Damaged canes are more susceptible to injury during the winter months.

  • If left untreated, rednecked cane borers can infect a majority of the canes, significantly impacting yield.

Management & Treatment:

  • Look for a faint brown-green line circling damaged stems in mid-summer. Snip below the affected areas.

  • A slight S curve is an indication of infected canes; crippled leaves may surround the area.

  • Split the cane at the gall to find overwintering grubs.

  • Prune and destroy infested stems as soon as galls are visible.

  • Look for adult beetles during daylight hours in early to mid June.

  • Parasitic wasps and fungal diseases are effective controls.

References: NC State Extension, UK College of Agriculture, Food & Environment, Michael Phillips, “The Holistic Orchard”, and Patrick L. Byers, Horticulture Specialist