Adult Xylosandrus germanus
Xylosandrus germanus (Blandford), Coleoptera:
Scolytidae, also known as the black stem borer (BSB) is originally from southeast Asia. This
beetle has been found in at least 17 states, primarily in the eastern
BSB is reported to attack over 200 species of
plants in 52 families, although it prefers hardwoods. Some hosts of concern to
Signs of infestation:
l Apparently healthy hosts may be attacked.
l Entrance holes are approximately 1 mm in diameter and round (Fig. 1). Long toothpick-like strings of compacted boring dust may be found emerging from these holes (Fig. 2). Unfortunately, other wood boring insects in Oregon cause similar damage.
l Hosts with a diameter of less than 2.5 inches (~6 cm) are preferred, but injured or stressed larger trees can be attacked. Newly transplanted trees are especially vulnerable.
l Adult beetles are small, stout, cylindrical, dark brown to black, and about 2-2.5 mm in length. Adults are unlikely to be seen and can only be identified by a trained entomologist.
It poses a threat to:
BSB poses a threat to the nursery and orchard industries, as well as ornamental plantings, due to its apparent preference for attacking saplings and small diameter broad-leafed trees and shrubs, causing girdling, stunting, and death. It can attack and kill larger trees, particularly if they are stressed.
Infested woody nursery stock, raw wood products,
crating and packing material, firewood, and raw logs are all means by which BSB
could be brought into
Adults and larvae feed on a symbiotic fungus (“ambrosia”) grown on wood tissue, not on the wood itself. Adults can be present from March through July. Females are the only sex to fly and leave the brood galleries. Males are flightless and remain inside. Females overwinter in galleries or in leaf litter near the base of trees. When conditions are right in the spring, they emerge and attack hosts. Females bore a tunnel with a brood chamber and one or more
branches into the sapwood and sometimes the heartwood. Eggs are laid in the brood chamber, and larvae hatch and feed on the symbiotic fungus growing on the gallery walls. There may be up to 100 larvae per gallery and usually two generations per year, although three generations per year are known to occur in the southern parts of the beetle’s range.
Figure 1. Entrance hole. By G.K. Douce. The University of Georgia, www.forestryimages.org
Figure 2. Toothpick like boring-dust string.
By G.K. Douce, The University of Georgia, www.forestryimages.org
If you think you.ve
found BSB, please contact the ODA. Thank you for your cooperation.
If you think you.ve found BSB, please contact the ODA. Thank you for your cooperation.
of Agriculture, Plant Division
Oregon Department of Agriculture, Plant Division
635 Capitol St. NE,
Salem, Oregon 97301
635 Capitol St. NE, Salem, Oregon 97301
Phone: (503) 986-4636
The Oregon Invasive Species Hotline: 1-866-INVADER (1-866-468-2337)
Phone: (503) 986-4636