| Two different cane boring beetles, raspberry cane
borer and red-necked cane borer, can cause damage
on brambles such as raspberry and blackberry.
Occasionally, the raspberry cane borer may also
cause damage on roses.
Symptoms and Diagnosis
RASPBERRY CANE BORER: Twigs are girdled
causing younger shoot tips to wilt and eventually
die. The bases of girdled areas show a purple
discoloration.
RED-NECKED CANE BORER: Random areas on
branches may become swollen or enlarged. These
areas can be several inches long and at least 1/2
inch diameter. Sometimes branches may break off
where swelling has occurred. Holes in leaves caused
by the feeding of the adult beetles should also be
evident.
Life Cycle
RASPBERRY CANE BORER: Raspberry cane borers,
Oberea bimaculata, are long-horned beetles. Their
black bodies are about 1/2 inch long, and they have
prominent antennae that may be as long as, or
longer than, their bodies. They have a yellow
prothorax with two black dots. Adults emerge in
June. Females will insert single eggs into punctures
that they make in the twigs; twigs may be girdled
above and below these punctures. Larvae girdle the
trunks from the inside and remain to bore
downward through the trunks for two winters before
pupating and finally emerging as adults.
RED-NECKED CANE BORER: The red-necked cane
borer beetle, Agrilus ruficollis, has a blue-black
metallic body with a copper-red thorax. Females lay
their eggs on the bark of the canes, near the base of
a leaf. The white grubs are 1/2 inch long and can be
found feeding within the canes, near the swollen
and discolored areas. Adult borers can be found
feeding on the foliage in late spring or summer.
There is one generation per year.
Integrated Pest Management Strategies
1. Prune all canes that show signs of infestation. If
you prune after wilting first occurs, you only need
to prune about an inch below the wilted part; if
you wait to prune a wilted cane, a longer cut
must be made to insure that you remove the
feeding larva. Prune girdled canes the first winter
after observing damage in order to kill raspberry
cane borer larvae. Otherwise, they will continue
to feed and bore through until they have
completely destroyed the cane and reached the
ground to pupate the next winter. Remove canes
after red-necked borer damage has been observed
by late spring the next year so that adults don't
get a chance to emerge.
2. Destroy any wild brambles that may be
bordering your property. They may also be
hosting cane borers.
3. Apply insecticides. Both adults and larvae can be
controlled with insecticides. Apply rotenone
when adult beetles are most active prior to bloom
in order to achieve the most success. If needed,
apply a second spray once petals have fallen.
Spray or paint trunks and branches of infected
bushes with rotenone, pyrethrins, or
methoxychlor so that larvae are destroyed before
they have a chance to burrow into the wood. | 
