Thousand cankers disease (TCD) has caused dieback and death of eastern black walnut (Juglans nigra) in urban areas of the United States. Walnut timber and nut producers are greatly concerned about potential losses due to this emerging disease. A Forest Service scientist, in collaboration with partners at Purdue University, collected ambrosia beetles, bark beetles, and weevils colonizing main stems and branches of J. nigra trees exhibiting TCD symptoms in Ohio. Collected insects were identified and then evaluated for the presence of the TCD canker causing fungus, Geosmithia morbida, on their bodies. Two ambrosia beetle species (Xylosandrus crassiusculus and Xyleborinus saxeseni) and one weevil species (Stenominus pallidus) accounted for 149 of 155 collected specimens. G. morbida was detected on 22 to 65 percent of the individuals of these three species, as well as on two emerged walnut twig beetles (Pityophthorus juglandis). The latter species was previously the only known carrier of the fungus. The fungus-carrying ambrosia beetles may exacerbate TCD progression on J. nigra in affected areas. Additional insect species carrying G. morbida may expand the distribution of the G. morbida beyond those areas reached by WTB. Options for monitoring these additional species are under consideration by several eastern states.