Notes on Raspberry Insects
Raspberry Crown Borer
Identification
Affected canes wither and die or growth is limited and fruit is small.
Eventually, primocanes become so few in number that the planting dies
out.
Mature raspberry crown borer larvae are 2.5 cm, cream coloured larvae
with brown heads and obvious legs. The adult is a clear-winged moth with
a wingspan of 2.5-3.0 cm. The yellow bands across its black abdomen cause
it to resemble a yellow jacket wasp.
Raspberry crown borer larvae close-up
Raspberry crown borer larvae
Period of Activity
The adult lays its eggs on plant foliage in summer; larvae travel to
the base of the cane to overwinter. They tunnel into the cane and crown
the next spring. Larvae spend two years in the crown and root area before
they emerge as adults. They burrow at the base of the cane, in larger
roots and in the crown. Around harvest time of the second summer, they
pupate and emerge from the crown.
Monitoring
- To diagnose this pest dig up crowns and look for larvae, sawdust-like
frass and tunnels. Cut through the crown with clippers or shears to
look for larvae.
- Canes that grow out of infested crowns can sometimes be pulled or
tugged away from the crown to reveal borer damage and frass.
Management notes
Insecticides are targeted at the base of the cane in fall or early spring
before the larvae tunnel in. Treatment is required for two years to break
the cycle of this pest.
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