Pest profile

Raspberry Crown Borer

Pennisetia marginatum · Lepidoptera: Sesiidae[2]

Raspberry crown borer is the most devastating pest of blackberries and raspberries in Kentucky.[1]

Raspberry crown borer moth, a black-and-yellow clearwing moth that resembles a yellowjacket, on a plant
Raspberry crown borer moth, a black-and-yellow clearwing moth that resembles a yellowjacket, on a plant. (c) Linda Watson, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Adults are clearwing moths that look like medium yellowjackets, but with noticeable scales on the body and wings.[1]
  • Signs include sawdust-like frass at cane bases, swelling at the base and 1/4-inch tunnels seen when pruning.[1]

Look-alikes

Look-alikeHow to tell them apart
YellowjacketsYellowjackets have few hairs and no scales; the moth has visible scales.[1]

Where it lives

It's a common pest of blackberries and raspberries throughout Kentucky.[1]

US map: public records from 35 states since 1990 (GBIF).

Biology and life cycle

Moths fly from July through September and lay eggs singly under leaves.[1]

In Kentucky larvae probably need two years to develop, tunneling in canes and roots.[1]

Damage and signs

  • Canes die early, grow spindly and have smaller leaves.[1]

Health risk

It feeds on plants; UK Extension mentions no risk to people.[1]

Control

Sanitation

Remove wild brambles near the planting, and dig out and destroy infested canes and crowns.[1]

Biological control

Soil drenches with insect-killing Hb nematodes have succeeded against crown borers in trials.[1]

Common questions

Why are my blackberry canes dying?
Raspberry crown borer larvae in the crown and roots are a common cause.[1]
Is the yellow-and-black flier a wasp?
It may be the raspberry crown borer moth, which mimics a yellowjacket.[1]

Sources

  1. University of Kentucky Entomology (ENTFACT), “Raspberry Crown Borer (ENTFACT-226).” entomology.mgcafe.uky.edu/ef226 (accessed 2026-10-06)
  2. iNaturalist, “Pennisetia marginatum taxon page (order and family).” www.inaturalist.org/taxa/477881 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.