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How to Manage Pests
UC Pest Management Guidelines
Apricot
Shothole
Borer
Scientific name: Scolytus
rugulosus
(Reviewed 11/07,
updated 11/07)
In this Guideline:
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Shothole borers are tiny brown or black beetles.
Their white legless grubs mine the sapwood of the tree and often reduce it to
powder. Adult females bore tiny holes in the bark and lay eggs in
the cambium layer of the tree. When the eggs hatch, young larvae feed and
excavate secondary galleries at
right angles to the egg gallery. The outline of the gallery system resembles a
centipede. There are from one to three generations each year.
DAMAGE
Normally a number of shothole borer adults invade a tree at the same
time. Healthy trees exude resin, which usually kills the insects. If the tree
has injured or weakened areas, this resin buildup does not develop and the
invasion is successful. Ultimately, larvae may girdle the tree, or tree part,
and cause its death.
Shothole borers invade trees that have been previously damaged. The
nature of this damage dictates the course of preventive action. To prevent
attack by this beetle, maintain trees in a sound and vigorous condition, with
sufficient fertilizers, water, and sunburn prevention to keep uninfested tree
limbs from becoming damaged. Pruning can be helpful in eliminating areas in
older trees infested with shothole borer. Severely infested trees should be
removed. Burn or remove all infested wood from the orchard before the growing
season starts. Do not leave pruned limbs or stumps (healthy or infested) near orchards
(for example, in woodpiles) as beetles can emerge from these materials before
they dry out and migrate into orchards. Spraying for this insect is not
recommended.
IMPORTANT LINKS
![[UC Peer Reviewed]](/IMAGES/logo-ucpeerreviewed.jpg)
UC IPM Pest Management Guidelines: Apricot
UC ANR Publication 3433
Insects and Mites
W. W. Coates, UC Cooperative Extension, San Benito County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
K. R. Day, UC Cooperative Extension, Tulare County
K. A. Kelley, UC Cooperative Extension, Stanislaus County
J. L. Caprile, UC Cooperative Extension, Contra Costa County
Acknowledgment for contributions to Insects and Mites:
L. C. Hendricks, UC Cooperative Extension, Merced County
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