Bugs: An Out of the Box Weed Management Tool

Battling noxious weeds can be one of the most challenging natural resource issues landowners encounter. GVLT works with conservation easement landowners to explore all of the options available to help tackle the weed problem and care for their property and resources. Chemical herbicides and traditional mowing or hand pulling are the most common tools. These traditional methods can be very successful if implemented at the right time, but they can be challenging on properties that have areas that can be overlooked due to difficult or steep access or that are not economically feasible for traditional control methods. At GVLT we’ve been scratching our heads for a few years trying to figure out how to develop a baseline of control for weeds like knapweed and St. John’s Wort in the Bozeman Pass area, where the terrain is too steep or inaccessible for traditional methods. So we decided to go all in and try an alternative approach: Bio-Control Insects.

Bio-control insects are bugs that are native to the ecosystem where the most aggressive invasive weeds originated from. In their native ecosystem, the insects feed on a particular plant, thus reducing its viability and seed production capacity. These natural predators (bugs) keep each plant species in check so that it does not take over and dominate the plant community and reduce plant species diversity across the landscape. When weeds arrived in our area, they were not followed by their natural predators. In its new environment, the plant became a noxious invader and began to occupy more than its fair share of the landscape.

Researchers have identified several beneficial insects and collaborated with the US Department of Agriculture to approve the release of certain classes of insects that can help to reduce the prevalence of noxious weeds over time by impacting seed production and the health of individual weedy plants. Over the past couple of months GVLT has partnered with ten of our conservation easement owners and several bio-control insect collectors to release just over 12,000 bugs that will specifically impact the viability of spotted knapweed and Canada thistle in the Bozeman Pass wildlife connectivity corridor. We hope this effort will create a baseline of control, especially in steep terrain that is difficult to access for herbicide application.

*The insect in the header image is a Cyphocleonus achates; Spotted Knapweed root boring weevil