Raspberry crown borer

Look for a clear-winged moth resembling a yellow jacket, about 1 inch wingspan, with black body and four yellow abdominal stripes. White larvae with brown heads tunnel into crown tissue and roots at or below soil surface. Canes break easily during winter tying, and swelling with sawdust-like frass appears at entrance holes.

Inspect cane bases in winter and early spring for young larvae before they grow large. Remove and burn heavily infested plants. Ichneumonid wasp Pterocormus chasmodops provides natural control in Washington. Choose resistant cultivars and maintain optimal growing conditions to support crown vigor.