Raspberry Crown Borer

Crown Borers damage floricanes at their base, causing them to wilt and die. Entire plants may be killed.

Raspberry planting with single dead raspberry plant. Dead plant is devoid of leaves.
Photo courtesy D. Johnson, University of Arkansas

Look for burrows at the base of canes and in the crown and roots.

Close up of root base of dug-up raspberry plant. There is no bark 2-3 cm above the root zone, and a small hole the size of a large pinhead is visible in the base of the stem.
Photo courtesy D. Johnson, University of Arkansas

Adult crown borers are clear-winged moths that resemble yellow jackets. They emerge from July to September.

Wasp-like insect on leaf, viewed from above. Insect is black with thin horizontal yellow stripes and yellow legs. Head and antenna are black.
Adult crown borer.

Photo courtesy D. Johnson, University of Arkansas

Crown borer eggs are laid singly on the undersides of leaves.

Dry raspberry leaf with multiple shiny brown eggs shaped like sesame seeds.
Crown borer eggs on leaf underside.

Photo courtesy D. Johnson, University of Arkansas

Larvae burrow down individual canes into the crown. A single larva may kill several canes on one plant.

Raspberry cane cut in half longitudinally. The exposed pith of the cane is marked by several brown, vertical stripes that look like larval tunnels.
Photo courtesy D. Johnson, University of Arkansas

Dark red pupal skins attached to the lower section of canes/crown are also a characteristic sign of crown borer infestation.

Dug-up raspberry plant with an inchlong, brick red pupal skin attached near the junction of roots and stem. The pupal skin is mostly intact and tube-shaped.
Red pupal skin of a crown borer on raspberry.

Photo courtesy D. Johnson, University of Arkansas

More information:

Use these resources if you need additional help with diagnosis and to find solutions to your problem.