To start with, Dr. Cipollini has found emerald ash borer-infested white fringe trees at many sites in Ohio and around Chicago, beyond the formal study sites -Spring Grove Cemetery and Arboretum in Ohio and The Morton Arboretum outside of Chicago- reported in the paper. From these additional observations it seems emerald ash borers infest white fringetrees whenever they overlap.
So why has no one noticed this before? Partly because no one was looking but also because the states first infested with emerald ash borer, like Michigan, are outside the range of white fringetree. Also, Dr. Cipollini has noticed that attacks on white fringetree are not always successful. He finds galleries below the bark that did not yield adults and the diagnostic D-shaped exit hole. Also, white fringetrees heal over exit holes very quickly. These factors mean that live infested white fringetrees are difficult to detect. In recently infested states where white fringetree is common, like North Carolina, this phenomenon may be more noticeable.As to whether a adaptation or a genetic anomaly allowed some emerald ash borers to infest white fringetrees -the fluke or phenomenon question I raised- Dr. Cipollini sees it as a phenomenon based on the many observation they have made and genetic work showing that borers from fringetrees are not different than ones that infest ash trees.
Experiments from Dr. Cipolinni’s lab show that white fringetrees smell a lot like ash trees to insects; they have a similar volatile profile. Thus, when emerald ash borers become established in a new area they attack both tree species if they are available. In this way North Carolina could make a good experiment to document when fringetrees get attacked relative to their proximity to ash trees and emerald ash borer arrival. Emerald ash borer spread is just underway in NC and we have a lot of white fringetrees.