General Overview:
There are 30 non-native ambrosia beetle species in North America but only a half dozen are serious insect pests within nurseries, pecans & apples. The Xylosandrus species of beetle borers are native to southeast Asia & were first reported in the United States during the early 1930s (black stem borer). Today they are found in 29 states. Two ambrosia species found in NJ nurseries cause serious damage to trees. (1) The black stem borer (Xylosandrus germanus) (~2 mm) has attacked more than 200 tree species (fig.1). (2) The granulate (Asian) borer (Xylosandrus crassiusculus) (~2.5 mm) has attacked more than 120 tree species (fig.2). Both species are a threat to trees that are stressed. A 3rd species, the invasive redbay ambrosia beetle (Xyleborus glabratus), was first found in Louisiana in 2014. A major difference is it will also attack trees not under stress. It is not presently found in NJ, but it is moving north. The concern is the impact it may have on sassafras forests.
Fig. 1: An adult female ambrosia black stem beetle borer. Photo Credit: Brad Barnd, Bug Guide.net
Fig 2: An adult female ambrosia granulate borer. Photo Credit: Alabama Coop. Ext.
