Sometime in or before 1916 it came to the United States as a hitchhiker, nestled in the soil of some potted plants.

Perhaps someone smuggled them on board intentionally - who's to say?

But at some point around 1916 the Japanese beetle, with its shiny metallic green shell, left its home island and crossed the ocean to immigrate to America.

Nearly a century later, the crop and flower-eating insects have flocked to Kootenai County for the first time.

Not that the Idaho State Department of Agriculture is thrilled about the new arrival.

It's the opposite, in fact

"We're a little more than alert," said Mike Cooper, bureau chief in the department's plant division, on what could be Idaho's newest problem - possible infestation. "I'd say we're concerned."

The insect, quite frankly, is a pest, according to the department.

The USDA looks down on the Japanese beetle too, working with commercial flights and delivery companies Fed Ex and UPS at ports back east to inspect for the intruder.

Despite these efforts, the Japanese beetle has worked its way west, including Idaho.

"It's when you start catching dozens, you start to worry," said Cooper, which is exactly what started happening around Boise earlier this month. "That kind of raises an eyebrow."

The beetle has always been spotted - and trapped - in southern Idaho singly or by pairs since the early 1990s. No big deal when they show up in spots, in low numbers. But earlier this month they've caught two dozen, more in the last two weeks than they have in 25 years.

And for the first time up north, as two were trapped in Post Falls recently. Cooper didn't know the exact location except that it was on commercial property near Interstate 90.

"When a population gets going, they'll get going by the thousands," Cooper said.

Which is what the concern is.

What does the beetle - about a half inch long with copper-brown wing covers atop its green coat and white stripes on the side - do?

Eats and destroys lots of things.

It has around 300 hosts, including trees, rose bushes, flowers, stonefruits, and garden and field crops. They leave holes and skeletonized leaves. The larvae, or grubs, live under the soil surface and destroy patches of turf by feeding on roots of grass. When they eat in numbers, they can wipe out entire plots.

Asked if they provide any benefit, Cooper said: "None that I know of."

But the state isn't sounding the infestation alarm yet. It hasn't noticed crop damage. But the department is setting multiple specially-designed traps in the isolated areas to try and get a better gage of the numbers.

It is suspected the beetles migrated from the East Coast, because the east had a swell in numbers last year. The beetles need moist soil to live, however, and because the Midwest is suffering from drought, the state doesn't expect them to survive a cross-country journey this year - so if they can trap the ones already here, the population might not grow.

If you suspect you have found a Japanese beetle, seal a dead specimen or two in a sandwich bag and mail in a regular envelope to: Idaho State Department of Agriculture, Plant Industries Division, P.O. Box 790 Boise, ID 83701 and include your name, address and phone number, or call (208) 332-8620 to report the possible find.