The interloping insect, a native of China, is advancing across the United States, having been spotted in St. Paul, Minn., for the first time this summer.
"The North American ash has just shown no resistance to emerald ash borer, so its chance of surviving is essentially zero," said Jeff Hahn, an entomologist with the University of Minnesota extension office.
While an effective end to the forest threat may be years, or even decades off -- if at all -- that doesn't mean U.S. scientists have raised the white flag of surrender, the St. Paul Pioneer Press reported Monday. Their first goal is to slow the ash borer's advance.
Entomologists in Michigan are studying whether wasps can be enlisted in the war to kill the ash borer's eggs and larvae. Ohio tree breeders are trying to develop a borer-resistant version of the North American ash.
Minnesota researchers say there are effective, if expensive, chemical alternatives to save specific trees.
The insect was first found in the United States in 2002, near Detroit. It is now in 13 states and two Canadian provinces.
"The spread rates are much higher than we would have hoped for or anticipated," said Steve Katovich, a U.S. Forest Service entomologist in St. Paul.