New Records of Two \u3ci\u3eXyleborus \u3c/i\u3e (Coleoptera: Scolytidae) in North America

New American locality records are given for two exotic ambrosia beetles (Coleptera: Scolytidae) in the genus Xyleborus. Xyleborus pfeili (Ratzeburg), a widely distributed Old World species, is reported for the first time in North America, from three counties in Maryland. Xyleborus californicus Wood, of northern Palearctic origin, but previously established in the western United States, is reported for the first time from Maryland, Delaware, South Carolina and Arkansas. Diagnoses and descriptions are given for the two species, along with scanning electron micrographs of key characters. Modifications are made to a previous key to include these new additions to the eastern North American ambrosia beetle fauna