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Shelterbelt Centre Pest Leaflets
Western Ash Bark Beetle
Hosts: Ash
Appearance and Life History:
The Western ash bark beetle
overwinters as an adult in the
bark at the base of living ash
trees. Adults are oval-shaped,
2-3 mm in length and may vary
from light reddish-brown to
dark brown. In early May,
adults emerge and move to
small branches of stressed ash
trees to seek egg-laying sites.
After mating, females tunnel
into the sapwood to deposit
eggs in galleries that encircle
the branch. After hatching, the
larvae tunnel away from the
main gallery. The larvae are
white, legless, have a brown
head, and are 2 to 4 mm in
length. New adults emerge and
feed before seeking hibernation
sites in September and October.
![egg deposit in bark](/web/20061210135308im_/http://agr.gc.ca/pfra/shelterbelt/pest/87-0030.jpg)
![western ash bark beetle](/web/20061210135308im_/http://agr.gc.ca/pfra/shelterbelt/pest/87-0028.jpg)
Damage: Galleries constructed
by the female often encircle a
branch. Leaves will often wilt
and turn bright yellow from the
gallery outward. An egg gallery
can be identified by a row of
ventilation holes about 1 mm in
diameter and 5 mm apart in the
bark. The area around the egg
gallery is discolored and
sunken, especially late in the
growing season. The Western
ash bark beetle generally infests
only weakened or stressed
trees, causing minimal damage.
When many trees are stressed,
bark beetle populations can
increase rapidly and cause
significant damage. There are
two other species of ash bark
beetles common in the Prairies,
but they are of no economic
importance since they breed
and feed only in the branches of
dead ash trees.
Presently, there is no
insecticides registered for
control of ash bark beetles.
Dead, weakened or infested
branches should be pruned and
buried or burned before bark
beetles adult emerge in July.
For more information contact:
PFRA Shelterbelt Centre
Indian Head, Sask. S0G 2K0
Phone: (306) 695-2284 or Fax: (306) 695-2568
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