HAZEN - Don't worry about ants spoiling the picnic along the Knife River these days.

The spoiler is millions of green worms, dangling from the trees on long webby strings.

The army of canker worms that has invaded a 30-mile stretch of the river makes kids shriek in disgust when they find them in their hair or crawling around on their T-shirts.

It's a nasty problem. And it's one only time will cure. In the meantime, the trees probably won't die unless conditions become extremely dry and cause more stress.

The canker worms have acted like an army equipped with napalm, denuding hundreds, likely thousands, of trees practically overnight.

The worm infestation appears to be working its way downriver.

It was reportedly severe in the upper reach of the Knife River from Golden Valley and Zap, downriver to Beulah last summer.

This year, those areas are undergoing a secondary infestation, and the worms have found their way east to Hazen and Stanton, as well.

Joel Nichols, a community forester with the North Dakota Forest Service, said the trees look bad, and the situation makes people nervous.

He's not worried. Not yet.

The unusual wealth of rain this spring will go a long way toward keeping the trees viable.

He said the defoliation means the worms are peaking out and soon will go into a dormant stage.

In about two to three weeks, the leaves should reappear. Keep your fingers crossed that they do, if they're not tied up picking worms off your clothing.

Nichols said the infestation will likely last three years. Unless conditions are abnormally dry, or if the natural worm predators of parasitic wasps or disease don't take hold, the fourth year should mark the end of it.

In the meantime, trees won't flourish and some may lose limbs. But normally, a canker worm invasion won't kill the trees.

The worms favor the American elm tree. Since many of those have already died of Dutch elm disease, they've moved on to box elders, ash and Siberian elms, all trees natural to a prairie waterway.

Beulah Councilman Robert Schutt said last year's infestation was so severe in Beulah that the city brought in a professional sprayer, Wade Becker, to have at the worms.

Becker said he used a pressure gun and the chemical Sevin. Last year was dry, so the chemical hung on and made a difference, he said.

This year, the worms are back in some areas, and Becker has been "extremely" busy spraying trees on public and private property.

"People have put a lot of time into getting their trees big, and they figure they ain't going to let the worms kill them," Becker said.

Nichols said chemical sprays will reduce the number of worms, but their pervasive numbers make them hard to control that way.

He likes a chemical "BT" because it's bacteria-based. The cost of spraying an entire river course would be very expensive, and most sprays will also work against the solution because they kill natural worm predators.

Patience and rain are two things that will help.

There is one good side to all the worms hanging around.

Birds love them.

Bird-watchers along the Knife River should have a field day right now, and mom and dad finch and robin won't have to fly far for food.

(Reach reporter Lauren Donovan at 888-303-5511 or lauren@;westriv.com.)