Granulate Ambrosia Beetle
Introduction
Ambrosia beetles are very small insects that do not feed on trees; rather they create vast networks of tunnels or galleries in wood to “farm” ambrosia fungi upon which both adults and larvae feed. Ambrosia beetles typically attack recently dead, dying, or severely stressed trees. They also attack green logs and unseasoned lumber. The activity of ambrosia beetles can result in considerable degradation of lumber. Granulate ambrosia beetle, previously called ‘Asian’ ambrosia beetle, was introduced into South Carolina in the 1970s and has since spread to many states in the eastern and midwestern U.S. and the west coast.
Identification
Adult beetles are rusty brown and very tiny, about the size of the year on a penny. Female beetles are about 3 millimeters long, and smaller males are about 1.5 millimeters long. Symptoms of infestation include wilting, branch dieback and reduced growth. Closely inspecting the trunk of infested trees will reveal 1 millimeter holes in the bark. Young trees often die, but established trees can sometimes survive when treated.
Management
Rapid harvesting and utilization of dead and dying trees, fresh cut logs, and lumber will reduce infestations and the severity of wood degradation. Living trees infested by ambrosia beetles will likely not survive, and should be removed if they present a hazard. Be aware that ambrosia beetles can attack isolated branches and wounds; these infestations are not a threat to tree health. Control is not recommended in forest or landscape situations because the beetles will not attack even moderately healthy trees.
