BOZEMAN, Mont. -

Montana agriculture officials are warning of a potential threat to Montana's urban forests.

In Helena, capitol grounds crews tagged trees with a warning for the emerald ash borer, an invasive beetle discovered in Michigan in 2002.

Adult beetles do little to seriously damage the tree, but the larvae eat the tree's inner bark, damaging the tree's system for transporting water and nutrients.

It hasn't been seen in Montana yet, but it is making its way west. The most recent outbreak was reported in Colorado last fall.

Ian Foley, with Montana's Pest Management Program said, "In central Montana, we've been dealing with mountain pine beetle for the last 5 or so years; this will be very much like mountain pine beetle for the urban forests.  The cities in central Montana -- particularly Helena, Great Falls, Bozeman, Billings -- have a lot of green ash trees, and this beetle has the potential to kill all of those ash trees."

Ash is the most common tree in Bozeman. More than 6,000 line streets and parks.

The threat of an infestation by the emerald ash borer is one City Forester Ryon Stover is well aware of. He told us, "Some people will say 'It's not going to get here because we're an island in a sea of grass.' And other people will say 'It's just a matter of time.'"

The beetle is slow to spread on its own, but Stover says they can spread rapidly if people aren't careful. It can hitch a ride in firewood, from infested areas back east or even in wooden shipping pallets from Asia, where it's a native species.

"Down the interstate, down the railway." Stover said.

Stover says an infestation in Bozeman's ash trees would have a massive economic impact on the town, and would create an unsafe situation.

Stover explained, "Large parts of the tree fail, so then it becomes a hazard situation."

Bozeman is taking steps to minimize the potential destruction by limiting new sources of food for the beetle.

"For a public space," Stover said, "we're not approving any plans that have ash trees spec'd."

When a borer makes its way into a tree and plants its eggs, the infestation will quickly spread.

"Just a couple of bugs can actually kill the tree," explained arborist Scott Makoutz.

Makoutz operates Gallatin Tree Care. He says it's not a matter of if the beetles come to Bozeman, but when.

"It will be devastating. The quality of life in Bozeman will be diminished."

Makoutz cites losing shade and an increase of dusty wind. He says the town's best option is to plant a new generation of diverse trees as soon as possible, "So as these ash trees are infested we have another generation of trees in Bozeman to take its place."

Once an area is identified as having an infestation, the Minnesota Department of Agriculture lists two options for dealing with it. The first is simply removing the infested trees from the area. The second is using one of several insecticides to treat the tree. Using insecticide usually requires treating infected trees once a year for the remainder of their lifespan.

If you're concerned that your ash tree could be infected, you can call the Bozeman Forestry Department at to take a look at it. Their number is (406) 582-3204.