Emerald Ash Borer(EAB) is a beetle that lays its eggs within the fissures or cracks of the bark on ash trees predominantly native ashes to North America with preference in order to white ash (Fraxinus americana), black ash (F. nigra), and green ash (F. pennsylvanica). All three species are present in Jamestown yards with green ash occurring in the highest numbers and estimated between 30-40% of make-up of the urban forest. After the beetles eggs hatch the larvae borer down through the bark to the area between the bark and wood. It is here that the larvae makes a distinctly serpentine tunnel varying from a few inches to almost a foot in length. The width of their meanderings can be less than an inch to 3-4 inches. The tunnels start very small and as the larvae grows the tunnels become wider to up to about ½ inch wide. As adults the will borer out of the bark through distinct D shaped holes.
The adult beetle is flat on the top and rounded on its lower portion, thus the D shape holes. These can be important in identification although there are other borers that form similar D shaped holes but are not destructive. The EA Borer works alone but increases in numbers quickly and can dessimate a 10 inch tree in 2-3 years time. The borers work from the top branches of the tree and move downward, so the first symptoms will be a dieback in the tree’s canopy. By the time you are able to see D- shaped holes in the tree’s trunk it may be on its last legs. There are several insecticides that are currently under test and being sold as a short term cure be very cautious about these chemicals uptake by the tree is variable. The cost of many of these treatments are expensive and the results are questionable. Until the insect pest has been identified within the state, it is of no value to consider treatment as these chemicals only provide one year control it that. Call the City Forester for updated information and advice on whether it is an advantage to treat your tree.