Scolytus multi-striatus, an introduced European elm bark beetle, is the most important insect vector of the Dutch elm disease (Ceratostomella ulmi) in the U. S. This bark beetle has been found in parts of the following states Massachusetts. New Hampshire, New York, Connecticut. New Jersey. Pennsylvania, Delaware, Maryland, West Virginia. Ohio, Kentucky, and Indiana. The native elm bark beetle (Hylur-gopinus rufipes), a lesser vector of the disease, occurs in Canada and in the NE, SE and central parts of the U. S. The figure shows the known distribution of the Dutch elm disease fungus and S. m. in the U. S.