SHERIDAN — The first recorded history of biological control practices date back to Egyptian records around 4,000 years ago, where they used domesticated cats for rodent control, according to the University of California, Riverside Discoveries in Natural History & Exploration.
Insect predation, another popular form of bio control is first noted in Asia, where Chinese citrus growers place nests of predacious ants in trees that feed completely on foliage of the trees. Bamboo bridges were constructed to assist the ants in their movements from tree to tree. These practices moved to Yemen and then to North America, where many societies have colonized in date groves, ready to control various pests, according to the Association of Natural Biocontrol Producers.
Biological control is a component of an integrated pest management strategy that’s defined by Cornell University as the “reduction of pest populations by natural enemies and typically involves an active human role.”
The most successful practice of bio control Sheridan County has experienced is controlling leafy spurge, according to Luke Sander, supervisor of Sheridan County Weed and Pest.
Leafy spurge is a noxious weed native to Eurasia and has become widespread throughout the United States, according to the Minnesota Department of Agriculture. The Montana Weed Control Association describes the plant to have brown roots with pink buds; milky, latex sap in stems and leaves that stand 1 to 3 feet high with leaves 1 to 4 inches long; and yellow-green flowers.
Ranchers in the county shiver when they hear their neighbor has a large patch of leafy spurge.
“It’s been tough because there are areas we’ve spent thousands of dollars trying to spray and it won’t hardly touch it,” Sander said. “It can be pretty defeating going out year after year and not see very much progress after all the time and money spent trying to knock it back.”
The perennial weed spreads quickly and crowds out any other competing vegetation. When it goes untreated, it will steal large, open land, reducing land value drastically. Horses and cattle will not eat the weed due to the stem’s production of milky sap, which is known to cause scours and blisters in their mouth. Sheep and goats are known to eat the weed without any effects, but the animals are not effective when trying to eliminate the weed.
So, local ranchers and weed and pest personnel have had to adopt other methods for removal.
Local ranchers like David Kane and Lindy Burgess have seen tremendous success when adopting flea beetles instead of herbicide when attacking spurge.
“When we started I’d say nearly 35% of our place was covered in spurge,” Burgess said. “We’ve been at it for 20 years and I would almost guarantee that number is now around 1%.”
Kane has experienced similar success with removing spurge on his land.
“I truly feel bad when I hear guys complaining about spurge because mine’s all gone,” Kane said.
The bugs are formally bought through Weed and Pest and need to be spread the same day. They come packaged eating spurge so they’re ready to work. Kane, Burgess and Sander all agreed the higher number of bugs put out, the better success rates. Sander noted that the Weed and Pest typically dispersed around 5,000 bugs per area in a single release.
“People always think you have to really spread them out, but that’s a huge mistake,” Kane said. “They’re immobile and it’s our job to make it easy on them.”
The bugs are placed around June 1. They then grow, mature and eat the leafy spurge. Around August, the bugs will mature and producers gather the mature flea beetles ready to hatch their larvae.
“If you don’t have a net, just swing your hat around; I guarantee you’ll catch bugs,” Kane said.
Once the flea beetles are placed in the newest area, the bugs will then hatch their larvae and their larvae will attach themselves and grow to the root. Together they winter there and when the spurge matures, so does the insect. The flea beetle then begins eating the leafy spurge from the inside out and will move out once the root is completely deceased. This process takes up to three years to set up in its entirety.
Ranchers who have seen success with leafy spurge and flea beetles admit it is not a 100% solution. Once the leafy spurge disappears completely, the beetles have no resources to survive. Once the beetles are completely eliminated, there is no longer anything put in place to control the weed.
“In our experience, herbicide won’t totally eliminate spurge nor will the beetles,” Sander said. “But we’ve seen how effective using bugs can be and we want to use it as a tool to maybe achieve 80% or 50% of reduction. We understand that bugs aren’t completely effective, but in comparison of sending four or five guys out, paying for herbicide and man labor because it’s in a steep, hard to reach area, it’s worth trying to build the population over three or so years.”
Editor’s note: An earlier version of this article misspelled Luke Sander’s name. We regret the error.