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Since 1988, a swarm of bugs in North Dakota has multiplied from less than 100 to more than 2 million. Time to call the Orkin Man? Not quite. Instead of being exterminated, these bugs are the exterminators, helping Canadian Pacific Railway, Burlington Northern Santa Fe and local governments control hardy, noxious leafy spurge in the Dakotas and other states without spraying herbicides.

Common in Europe where it’s controlled by natural predators, leafy spurge was first documented in the United States in 1827. Capable of growing up to three-feet tall and sprouting roots up to 21 inches deep, the weed reached North Dakota in 1909 and now covers more than 5 million acres in 35 states, according to the U.S. Department of Agriculture (USDA).

Leafy spurge is hard to control with chemicals because of its deep root system, and is especially problematic in North and South Dakota, Montana and Wyoming, where it invades cattle and horse grazing pastures, and clogs railroad rights of way.

Culinary experts. But the USDA and railroads have found a way to fight the foreign invader: flea beetles. Although small in stature, the one-eighth-inch-long bugs have a mammoth appetite for leafy spurge.

Because the beetles won’t leave an area until they exhaust their sole food source, their dedicated munching skills help kill leafy spurge down to the root, as well as take a bite out of Class Is’ herbicide budgets.

“We used to spray these weeds with helicopters every year, but they would just grow back the next year,” says Grete Bridgewater, manager of environmental programs for CPR, which has been using flea beetles at more than 100 North Dakota and six western Canadian locations for nearly five years. “Now, the weeds won’t ever disappear, but we can get them down to a manageable level ... [and] control the vegetation in a natural setting.”

During the past eight years, BNSF vegetation-control crews have used the beetles to control leafy spurge in North Dakota, Wyoming and Montana communities that prohibit herbicide spraying in certain environmentally sensitive areas.

“This allows us to reduce the amount of herbicide needed and gives us another tool to control the spread of weeds in areas where you have limited options,” says BNSF Manager of Vegetation Control Gary Nyberg.

The hungry bugs also have eaten their way into the hearts of Barnes County, N.D., officials, who use the beetles to control leafy spurge at eight locations.

“We use the money we would have used to spray spurge to increase our control efforts on other weeds, like Canadian Thistle, or to investigate new weeds,” says Barnes County Weed Control Officer Jim McAllister. “It’s better to spray newer plants because they have smaller roots, but if spurge covers a wide area, it’s good to spray the borders so the spurge doesn’t spread, and then use the beetles.”

Thorough-breds. The bugs are bred for success in their native Europe, where they control leafy spurge. After they’re raised in laboratories, and subjected to eating-habit, gestation and other tests to ensure they pose no threat to local eco-systems, the bugs are released at U.S. locations in small numbers.

The beetles multiply quickly. In 1988, USDA released 77 beetles at a North Dakota location; today, the area contains more than 2 million bugs, says USDA Domestic Program Coordinator Dave Hirsch. The beetles go dormant in winter, then re-hatch in spring if they’re not killed by freezing temperatures or excessive precipitation.

So far, the miniature weedwhackers have performed as expected for CPR, controlling leafy spurge without threatening other plants or insects, or requiring herbicide applications.

“Now, we have biological controls [for] these weeds that don’t respect boundaries,” says Bridgewater. “The beetles help us get to the root of the problem.”

No pun intended.