Five prominent species of ash Tree in the eastern U.S. – including in New Hampshire – have been driven to the brink of extinction from years of lethal attack by a beetle, a scientific group says.

Ash Trees are a major part of eastern forests and urban streets, providing yellow and purplish leaves to the bounty of fall colors.

She led the scientific assessment that resulted in classifying the five species as critically endangered – meaning they are facing an extremely high risk of extinction in the wild.

A sixth species, the Carolina ash, was put in the less serious category of “endangered” because it might find some refuge from the infestation in the southern part of its range, which includes Florida, Texas and Cuba, Westwood said.

Dan Herms, an entomologist at Ohio State University who studies the ash borer, called it “the most devastating insect ever to invade North American forests.” It’s already the most expensive because it has killed so many urban trees that had to be removed, disposed of and replaced, which has cost billions of dollars, he said.