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Adult shothole borer.Scientific Name

Scolytus rugulosus



Common hosts include cherry, peach, plum, apple, and pear. They also breed in wild hosts such as wild plum, black cherry, and mountain ash.



Shothole borer symptoms on a tree.Adults cause some damage by feeding at the base of small twigs, but this may not be noticed unless large numbers are present. Most of the damage is done by the larvae feeding between the bark and wood of the trunk or limbs of host trees. This damage eventually girdles the limb or trunk and kills the affected part. Adult emergence holes through the bark give the appearance of a "shot gun" blast leaving "shot holes." The shothole borer chiefly attacks trees that have been weakened by the attacks of other borers or scale insects, winter injury, drought, disease, unsuitable soil conditions, or mechanical injury. They will, however, attack healthy trees that are near severely infested ones in which the beetles have bred in large numbers.


Life Cycle

Shothole borers overwinter as larvae in their feeding tunnels under the bark of host trees. They pupate in the spring and adults emerge in April or May. After mating, the female beetle bores through the bark and constructs an egg gallery parallel with the grain of the wood between the bark and cambium layer. The larvae feed for about one month in tunnels under the bark. After pupating and transforming to adults they chew small round holes through the bark and emerge. These small holes are the source of the common name. Soon after emergence the beetles begin to deposit eggs for another generation. There are probably three or four generations per year in Oklahoma.



The adult is a dark brown to black beetle about 1/10 inch long. The larvae are white, legless grubs with brown heads and are also about 1/10 inch long when mature.



Please contact your local county extension office for current information.

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