Emerald Ash Borer EAB The emerald ash borer is a metallic green wood boring beetle which is about 1 to 15 cm in length. Ash trees belong to the genus of flowering plants called Fraxinus. Scientists Move Closer To Ash Tree Resistant To Dieback Ash Tree Tree Art Tree The beetle arrived in North America from Asia and was first noticed in 2002 in Detroit. Ash tree disease pictures . These beetles attack all native species of ash trees. This Gardenerdy article tells you about different diseases in Ash trees along with their treatment. Learning how to identify these diseases will help you manage them properly. The number one disease of Ash trees is caused by the larvae of the Emerald Ash Borer which bore S-shaped tunnels under the bark of the Ash Tree. Ash genus Fraxinus is found throughout many of the forests in eastern North America and it is a commonly planted street and landscape tree. The emerald ash borer Agrilus planipennis Fairmaire is a shiny emerald green beetle that k...