Leafy spurge is an invasive, perennial weed from Eurasia that outcompetes native grass species thereby reducing forage available to cattle and wildlife. It spreads through rhizomes and seeds, and has deep roots which make it difficult to manage. The plant contains a milky sap that irritates the skin and is unpalatable to cattle. Leafy spurge is estimated to cost Montana ranchers $1.4 million dollars in lost forage and $2.5 million in chemical control per year. The N-Bar ranch utilizes flea beetles (Apthona nigriscutis, Apthona flava, Apthona lacertosa) and sheep grazing to manage between 850 to 1250 ha of rangeland infested with leafy spurge. The host-specific flea beetles consume spurge roots in their larval stage and consume the leaves as adults. Three bands of 850 ewes graze the spurge as well, weakening the plants, opening up the canopy, and reducing seed production. The combined effect of flea beetles and sheep grazing has been an effective weed management strategy. 

The ranch's goal for using flea beetles and sheep grazing is to reduce leafy spurge to just another member of the plant community. Flea beetle species Apthona nigriscutis and Apthona flava prefer dry sandy soil on south facing slopes. Athona lacertosa can tolerate a wetter and cooler environment in shade and in riparian areas but must be initially introduced in warm dry areas. Since flea beetle larvae feed on the spurge roots and mature in the soil, they cannot survive in flooded soils. Since the early 1980s, the ranch has reduced the area under chemical spurge control from 415 ha to 35 ha and dropped its herbicide usage for controlling leafy spurge from 500 gallons to 10 gallons per year. The N-Bar Ranch collects and distributes flea beetles to 11 other landowners in their watershed. They also collect and sell flea beetles for spurge management as a fundraiser for AERO, a Montana based sustainable agriculture organization.  

Minimize Toxics

Use of flea beetles and sheep to manage spurge can reduce the use of chemical herbicides. By using sheep and flea beetles, the N-Bar Ranch has reduced its herbicide use for leafy spurge control from about 500 gallons to 10 gallons from the early 1980s to the present.

Conserve Resources

Biological weed management reduces ranch expenditures. Flea beetles control spurge without additional costs for labor and machinery. The ranch receives a small fee from the sheep owner for allowing the sheep graze.

Manage Ecological Relationships

By introducing flea beetles to the system, there is now a natural check on the spread of leafy spurge. Sheep contribute to the management by exerting grazing pressure on leafy spurge. This dual herbivore system manages spurge without the need to control it using herbicides.

Maximize Long-Term Benefits

By reestablishing the balance between the exotic weed and its herbivorous pest, flea beetles act as a permanent weed management tool. 

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